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The inversions of an array indicate; how many changes are required to convert the array into its sorted form. When an array is already sorted, it needs 0 inversions, and in another case, the number of inversions will be maximum, if the array is reversed.

To solve this problem, we will follow the Merge sort approach to reduce the time complexity, and make it in Divide and Conquer algorithm.

Input and Output Input: A sequence of numbers. (1, 5, 6, 4, 20). Output: The number of inversions required to arrange the numbers into ascending order. Here the number of inversions are 2. First inversion: (1, 5, 4, 6, 20) Second inversion: (1, 4, 5, 6, 20) Algorithm

merge(array, tempArray, left, mid, right)

Input: Two arrays, who have merged, the left, right and the mid indexes.

Output: The merged array in sorted order.

Begin    i := left, j := mid, k := right    count := 0    while i <= mid -1 and j <= right, do       if array[i] <= array[j], then          tempArray[k] := array[i]          increase i and k by 1       else          tempArray[k] := array[j]          increase j and k by 1          count := count + (mid - i)    done    while left part of the array has some extra element, do       tempArray[k] := array[i]       increase i and k by 1    done    while right part of the array has some extra element, do       tempArray[k] := array[j]       increase j and k by 1    done    return count End

mergeSort(array, tempArray, left, right)

Input: Given an array and temporary array, left and right index of the array.

Output − Number of inversions after sorting.

Begin    count := 0       mid := (right + left)/2       count := mergeSort(array, tempArray, left, mid)       count := count + mergeSort(array, tempArray, mid+1, right)       count := count + merge(array, tempArray, left, mid+1, right)    return count using namespace std; int merge(intarr[], int temp[], int left, int mid, int right) {    int i, j, k;    int count = 0;        i = left;    //i to locate first array location    j = mid;        k = left;    //i to locate merged array location    while ((i <= mid - 1) && (j <= right)) {       if (arr[i] <= arr[j]) {    //when left item is less than right item          temp[k++] = arr[i++];       }else{          temp[k++] = arr[j++];          count += (mid - i);    //find how many convertion is performed       }    }     while (i <= mid - 1)    //if first list has remaining item, add them in the list        temp[k++] = arr[i++];     while (j <= right)    //if second list has remaining item, add them in the list        temp[k++] = arr[j++];         for (i=left; i <= right; i++)        arr[i] = temp[i];    //store temp Array to main array     return count; } intmergeSort(intarr[], int temp[], int left, int right) {    int mid, count = 0;       mid = (right + left)/2;    //find mid index of the array       count  = mergeSort(arr, temp, left, mid);    //merge sort left sub array       count += mergeSort(arr, temp, mid+1, right);    //merge sort right sub array                 count += merge(arr, temp, left, mid+1, right);    //merge two sub arrays    }    return count; } intarrInversion(intarr[], int n) {    int temp[n];    return mergeSort(arr, temp, 0, n - 1); } int main() {    intarr[] = {1, 5, 6, 4, 20};    int n = 5;    cout<< "Number of inversions are "<<arrInversion(arr, n); } Output Number of inversions are 2

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## Add An Element To An Array In Swift

In this article, you will learn how to add an element to an array in Swift.

Before you begin to learn element insertion into an array, you will need to understand the type of array.

Array Syntax let arrayName: [valuetype] = [array element 1, array element 1, ...array element n] var arrayName: [valuetype] = [array element 1, array element 1, ...array element n]

In Swift, we can declare an array with let for immutable and var for a mutable array. For an immutable array, we have to provide the array elements at the time of initialization.

How to Append an Element Into an Array?

Now, if you want to append an element to an array, we have to make it mutable using the var keyword. Let’s see how to append an element.

Syntax

To add an element to an array in Swift, you can use the append method of the Array type. This method adds a new element to the end of the array.

numbers.append(n)

Basically, you can pass the element to append in the given array.

Algorithm

Step 1 − Declare a mutable array

Step 2 − Call append() method to append an element

Step 3 − Print the output

Example

For example, if you have an array of integers called numbers and you want to add the number 25 to it, you can do it like this −

var numbers: [Int] = [10, 20, 4, 56, 2, 67, 78] print("Numbers before: (numbers)") numbers.append(25) print("Numbers after: (numbers)") Output Numbers before: [10, 20, 4, 56, 2, 67, 78] Numbers after: [10, 20, 4, 56, 2, 67, 78, 25] How to Add Multiple Elements at Once? Syntax

Yes, you can add multiple elements at a time like this −

numbers.append(contentsOf: [Array Elements])

Basically, you can pass an array to append all the elements into another array that is already mutable.

Algorithm

Step 1 − Declare a mutable array

Step 2 − Call number.append() function to append multiple elements

Step 3 − Print the output

Example var numbers: [Int] = [10, 20, 4, 56, 2, 67, 78] print("Numbers before: (numbers)") numbers.append(contentsOf: [40, 45, 50]) print("Numbers after: (numbers)") Output Numbers before: [10, 20, 4, 56, 2, 67, 78] Numbers after: [10, 20, 4, 56, 2, 67, 78, 40, 45, 50]

You can use the += operator to append elements like the following −

numbers += [40, 45, 50]

Remember that the append() method will add elements at the end of the array.

How to Insert an Element at a Specific Index in an Array? Syntax

In the insert() method, you have to pass an element and the index on which you want to insert that element.

Algorithm

Step 1 − Declare a mutable array

Step 2 − Call insert() method with element and index

Step 3 − Print the output

Example 1

If you want to insert an element at a specific index in the array, you can use the insert(_:at:) method. For example −

var numbers: [Int] = [10, 20, 4, 56, 2, 67, 78] print("Numbers before: (numbers)") numbers.insert(15, at: 1) print("Numbers after: (numbers)") Output Numbers before: [10, 20, 4, 56, 2, 67, 78] Numbers after: [10, 15, 20, 4, 56, 2, 67, 78]

This will insert the number 15 at index 1 in the numbers array, shifting the existing elements to the right.

Example 2

Note that you cannot insert an element into an array at an index that is outside the bounds of the array. The code will break with an exception like below −

var numbers: [Int] = [10, 20, 4, 56, 2, 67, 78] numbers.insert(15, at: 10) Output Fatal error: Array index is out of range Current stack trace: 0 chúng tôi 0x00007f27c596a2e0 swift_reportError + 50 1 chúng tôi 0x00007f27c59def40 _swift_stdlib_reportFatalErrorInFile + 112 2 chúng tôi 0x00007f27c56c9026 + 1425446 3 chúng tôi 0x00007f27c56c8c4f + 1424463 4 chúng tôi 0x00007f27c56c89ec + 1423852 5 chúng tôi 0x00007f27c56c8500 _assertionFailure(_:_:file:line:flags:) + 441 6 chúng tôi 0x00007f27c56b4461 + 1340513 8 swift-frontend 0x000000000058765a + 1603162 9 swift-frontend 0x000000000054c778 + 1361784 10 swift-frontend 0x000000000051c4ca + 1164490 11 swift-frontend 0x000000000051bb7c + 1162108 12 swift-frontend 0x0000000000510710 + 1115920 13 swift-frontend 0x000000000049be53 + 638547 14 libc.so.6 0x00007f27c721ab10 __libc_start_main + 231 15 swift-frontend 0x000000000049b96a + 637290 Stack dump: 0. Program arguments: /usr/bin/swift-frontend -frontend -interpret main.swift -disable-objc-interop -module-name main 1. Swift version 5.4.2 (swift-5.4.2-RELEASE) 2. While running user code "main.swift" /usr/bin/swift-frontend[0x5806484] /usr/bin/swift-frontend[0x5803f1e] /usr/bin/swift-frontend[0x580666c] /lib/x86_64-linux-gnu/libpthread.so.0(+0x12980)[0x7f27c8995980] /usr/lib/swift/linux/libswiftCore.so(+0x15c02a)[0x7f27c56c902a] /usr/lib/swift/linux/libswiftCore.so(+0x15bc4f)[0x7f27c56c8c4f] /usr/lib/swift/linux/libswiftCore.so(+0x15b9ec)[0x7f27c56c89ec] /usr/lib/swift/linux/libswiftCore.so(\$ss17_assertionFailure__4file4line5flagss5NeverOs12StaticStringV_A2HSus6UInt32VtF+0x1b9)[0x7f27c56c86b9] /usr/lib/swift/linux/libswiftCore.so(+0x147461)[0x7f27c56b4461] [0x7f27c8d3a0fc] /usr/bin/swift-frontend[0x58765a] /usr/bin/swift-frontend[0x54c778] /usr/bin/swift-frontend[0x51c4ca] /usr/bin/swift-frontend[0x51bb7c] /usr/bin/swift-frontend[0x510710] /usr/bin/swift-frontend[0x49be53] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xe7)[0x7f27c721abf7] /usr/bin/swift-frontend[0x49b96a] /usr/bin/timeout: the monitored command dumped core Illegal instruction

This error clearly indicates that the element cannot be inserted at the given index because it is out of range.

Conclusion

Swift provides two different methods to modify the array. Both methods are used in different situations. While you insert an element into an array, you have to take care of the index bound.

## What Are The Different Ways Of Copying An Array Into Another Array In Java?

In general, arrays are the containers that store multiple variables of the same datatype. These are of fixed size and the size is determined at the time of creation. Each element in an array is positioned by a number starting from 0. You can access the elements of an array using name and position as −

System.out.println(myArray[3]); Creating an array in Java:

In Java, arrays are treated as referenced types you can create an array using the new keyword similar to objects and populate it using the indices as −

int myArray[] = new int[7]; myArray[0] = 1254; myArray[1] = 1458; myArray[2] = 5687; myArray[3] = 1457; myArray[4] = 4554; myArray[5] = 5445; myArray[6] = 7524;

Or, you can directly assign values with in flower braces separating them with commas (,) as −

int myArray = { 1254, 1458, 5687, 1457, 4554, 5445, 7524}; Copying arrays

You can copy one array from another in several ways −

Copying element by element − One way is to create an empty array with the length of the original array, and copy each element (in a loop).

Example import java.util.Arrays; public class CopyingArray {    public static void main(String args[]) {             int integerArray1[] = { 1254, 1458, 5687, 1457, 4554, 5445, 7524};             int length1 = integerArray1.length;             int integerArray2[] = new int[length1];       for (int i=0; i<length1; i++) {          integerArray2[i] = integerArray1[i];       }       System.out.println("Original array: "+Arrays.toString(integerArray1));       System.out.println("Copied array: "+Arrays.toString(integerArray2));             String StringArray1[] = { "Mango", "Apple", "Orange", "Banana", "Cherries"};             int length2 = StringArray1.length;             String StringArray2[] = new String[length2];       for (int i=0; i<length2; i++) {          StringArray2[i] = StringArray1[i];       }       System.out.println("Original array: "+Arrays.toString(StringArray1));       System.out.println("Copied array: "+Arrays.toString(StringArray2));    } } Output Original array: [1254, 1458, 5687, 1457, 4554, 5445, 7524] Copied array: [1254, 1458, 5687, 1457, 4554, 5445, 7524] Original array: [Mango, Apple, Orange, Banana, Cherries] Copied array: [Mango, Apple, Orange, Banana, Cherries]

Using the clone() method − The clone() method of the class java.lang.Object accepts an object as a parameter, creates and returns a copy of it.

Example import java.util.Arrays; public class CopyingArray {    public static void main(String args[]) {             int integerArray1[] = { 1254, 1458, 5687, 1457, 4554, 5445, 7524};             int integerArray2[] = integerArray1.clone();       System.out.println("Original array: "+Arrays.toString(integerArray1));       System.out.println("Copied array: "+Arrays.toString(integerArray2));             String StringArray1[] = { "Mango", "Apple", "Orange", "Banana", "Cherries"};             String StringArray2[] = StringArray1.clone();       System.out.println("Original array: "+Arrays.toString(StringArray1));       System.out.println("Copied array: "+Arrays.toString(StringArray2));    } } Output Original array: [1254, 1458, 5687, 1457, 4554, 5445, 7524] Copied array: [1254, 1458, 5687, 1457, 4554, 5445, 7524] Original array: [Mango, Apple, Orange, Banana, Cherries] Copied array: [Mango, Apple, Orange, Banana, Cherries]

Using the System.arraycopy() method − The copy() method of the System class accepts two arrays (along with other details) and copies the contents of one array to other.

Example import java.util.Arrays; public class CopyingArray {    public static void main(String args[]) {             int integerArray1[] = { 1254, 1458, 5687, 1457, 4554, 5445, 7524};             int length1 = integerArray1.length;             int integerArray2[] = new int[length1];             System.arraycopy(integerArray1, 0, integerArray2, 0, length1);       System.out.println("Original array: "+Arrays.toString(integerArray1));       System.out.println("Copied array: "+Arrays.toString(integerArray2));             String StringArray1[] = { "Mango", "Apple", "Orange", "Banana", "Cherries"};             int length2 = StringArray1.length;             String StringArray2[] = new String[length2];             System.arraycopy(StringArray1, 0, StringArray2, 0, length2);       System.out.println("Original array: "+Arrays.toString(StringArray1));       System.out.println("Copied array: "+Arrays.toString(StringArray2));    } } Output Original array: [1254, 1458, 5687, 1457, 4554, 5445, 7524] Copied array: [1254, 1458, 5687, 1457, 4554, 5445, 7524] Original array: [Mango, Apple, Orange, Banana, Cherries] Copied array: [Mango, Apple, Orange, Banana, Cherries]

## C++ Permutation Of An Array That Has Smaller Values From Another Array

B = [1, 20, 10, 12] Output: 12, 22, 41, 13

Input: A = [2, 5, 9, 7], B = [1, 12, 4, 54] Output: 2 7 5 9

using namespace std; int main(){     int A[] = { 2, 5, 9, 7 };     int B[] = { 1, 12, 4, 54 };     int n = sizeof(A) / sizeof(int);     /***********************We are linking element to its position***********/     for (int i = 0; i < n; i++)         A_pair.push_back({A[i], i});     for (int i = 0; i < n; i++)         B_pair.push_back({B[i], i});     /***********************************************************************/     /*****Sorting our pair vectors********************/     sort(A_pair.begin(), A_pair.end());     sort(B_pair.begin(), B_pair.end());     int i = 0, j = 0, ans[n];     memset(ans, -1, sizeof(ans));     while (i < n && j < n) {                                             ans[B_pair[j].second] = A_pair[i].first;             i++;             j++;         }         else {             remaining.push_back(i);             i++;         }     }     j = 0;     for (int i = 0; i < n; ++i){                         if (ans[i] == -1){             ans[i] = A_pair[remaining[j]].first;             j++;         }     }     for (int i = 0; i < n; i++)         cout << ans[i] << ” “;     return 0; }

Output 2 7 5 9 Explanation of the Above Code

In this approach, we first link all the elements to their indices to still have their old index in it when we sort it. We sort both of the vectors of pairs now we greedily search for our answers as we move through both the arrays if we get an index of A_pair which has more excellent value than of B_pair, so we store that in our an array(and in the position of B_pair) else as we have sorted both the vectors, so we know that we won’t be able to use this value of A_pair, so we push that elements index in our remaining vector now we fill the array by the help of remaining vector, and then we print the answer.

Conclusion

In this tutorial, we solve a problem to find the Permutation of an array with smaller values from another array. We also learned the C++ program for this problem and the complete approach we solved. We can write the same program in other languages such as C, java, python, and other languages. We hope you find this tutorial helpful.

## Golang Program To Sort An Array In Descending Order Using Insertion Sort

Insertion sort is a simple sorting algorithm that works similarly to the way you sort playing cards in your hands. The array is virtually split into a sorted and an unsorted part. The elements from unsorted arrays are picked and placed at the correct positions in unsorted arrays, as a result, the array becomes sorted. Here we are going to learn different approaches to sorting an array in descending order using insertion sort in go programming language.

Syntax func append(slice, element_1, element_2…, element_N) []T

The append function is used to add values to an array slice. It takes number of arguments. The first argument is the array to which we wish to add the values followed by the values to add. The function then returns the final slice of array containing all the values.

func make ([] type, size, capacity)

The make function in go language is used to create an array/map it accepts the type of variable to be created, its size and capacity as arguments and returns the slice which we can store in the variable.

Algorithm

Step 1 − First, we need to import the fmt package.

Step 2 − Then, we need to start the main() function. Inside this function initialize an array of integers by using make() function and assign values to it by using append() function.

Step 3 − Then, we need to print the array on the screen using fmt.Println() function. Then use a for loop to iterate over the array and store the current element of the array in a temporary variable called key. Initialize a new variable and assign value to it by decrementing the index.

Step 4 − Now, use a for loop and check whether the current element is greater than the previous element.

Step 5 − If the condition is satisfied then swap the two values and decrement the current index in this inner loop.

Step 6 − Repeat the process until the whole array is iterated upon and print the final array thus achieved on the screen.

Step 7 − Now, start the main() function initialize an array, and store values to it. print the array on the screen.(For example 2)

Step 8 − Now, call the insertionSort() function by passing the array as an argument and store the result in a new array called result. (For Example 2)

Step 9 − Print the array obtained on the screen.

Example 1

In this example, we will write a go language program to sort the array of integers in descending order by using the insertion sort.

package main import "fmt" func main() { arr := make([]int, 0, 5) arr = append(arr, 5, 2, 4, 6, 1, 3) fmt.Println("The given array is: ", arr) for i := 1; i < len(arr); i++ { key := arr[i] j := i - 1 arr[j+1] = arr[j] j = j - 1 } arr[j+1] = key } fmt.Println("Sorted Array in Descending Order: ", arr) } Output The given array is: [5 2 4 6 1 3] Sorted Array in Descending Order: [6 5 4 3 2 1] Example 2

In this example, we will show how we can use an external user defined function to sort an array in descending order using insertion sort. The function that we create accepts the array to be sorted as an argument and returns the final sorted array as the result that we can print on the screen.

package main import "fmt" func insertionSort(arr []int) []int { for i := 1; i < len(arr); i++ { key := arr[i] j := i - 1 arr[j+1] = arr[j] j = j - 1 } arr[j+1] = key } return arr } func main() { arr := make([]int, 0, 5) arr = append(arr, 5, 2, 4, 6, 1, 3) fmt.Println("The given array is: ", arr) res := insertionSort(arr) fmt.Println("Sorted Array in Descending Order:", res) } Output The given array is: [5 2 4 6 1 3] Sorted Array in Descending Order: [6 5 4 3 2 1] Conclusion

We have successfully compiled and executed a go language program to sort an array in descending order using insertion sort along with examples. we have used two examples here one using the main() section of the program and other using the external function.

## Types Of Data Scientists: An Array To Choose From

Data scientists come in numerous flavors with various qualities that may suit various kinds of companies relying upon the sorts of issues or projects

Data Scientists have consistently been around – it is only that nobody realized that the work that these individuals are doing is called data science. Data Science as a field has emerged distinctly over the recent few years yet individuals have been working in the data science field as analysts, mathematicians,learning and actuarial scientists, business analytic practitioners, digital analytic consultants, quality analysts and spatial data scientists. Individuals working under these jobs are well furnished with data scientist skills and they are most demanded in the business. Data science has quickly developed as a challenging, lucrative and highly rewarding career. While developed nations got comfortable with it part of the way through the last decade, data science has received consideration on a worldwide scale after the exponential development of e-commerce in developing economies, particularly India and China. In the previous decade, there has been a significant change in perspective in the way the world shops, books holidays, makes transactions and basically everything else. Not all data scientists are made equal, particularly now that few “generations” of data scientists have entered and left organizations. Today, data scientists come in numerous flavors with various qualities that may suit various kinds of companies relying upon the sorts of issues or projects they are taking a shot at. Not to state that one sort is better or worse over another kind of data scientist — everything relies upon what a business is looking for.

Management Consultant

This classification traverses the junior business analyst and the ex McKinsey consultant. They share a common enthusiasm for Excel and their capacity to flaunt v-lookups and fancy formulas even to plan their house move. They are additionally the ones who have more passion for the business issue. For them, business comes first, data after. They needed to learn Python or R by need, not on the grounds that they enjoyed programming. They actually try to abstain from coding as much as possible and their code is by and large as re-usable as a single-use napkin. They have great instincts for the nuts and bolts of statistics however, they needed to learn concepts like p-worth or t-test the most difficult way possible. They are good at data science projects that bolster decision making, business-oriented processes, one-off projects.

Statisticians

This is data analysis in the conventional sense. The field of statistics has consistently been about number crunching. A solid statistical base qualifies you to extrapolate your enthusiasm for various data scientist areas. Hypothesis testing, confidence intervals, Analysis of Variance (ANOVA), data visualization and quantitative research are some of the important skills possessed by statisticians which can be extrapolated to pick up expertise in explicit data scientist fields. Statistics knowledge, when clubbed with domain knowledge, (for example, marketing, risk, actuarial science) is the ideal blend to land a statistician’s work profile. They can create statistical models from big data analysis, complete experimental design and apply theories of sampling, clustering and predictive modelling to information to decide future corporate activities.

Data Science for People

The consumers of the yield are leaders like chiefs, product managers, designers, or clinicians. They need to reach inferences from data so as to settle on decisions, for example, which content to license, which sales lead to follow, which medication is less inclined to cause a hypersensitive response, which site page design will prompt greater engagement or more buys, which email will yield higher income, or which explicit aspect of a product user experience is suboptimal and needs attention. These data scientists design, define, and implement metrics, run and interpret experiments, create dashboards, draw causal inferences, and generate recommendations from modeling and measurement.