Given an integer, k, and an array of integers, a, count the number of pairs of integers in a that sum to k. Complete the countPairs function in the editor below. It has two parameters: 1. An integer, k, denoting the desired sum 2. An array of integers, a, denoting the values to examine More points will be awarded for solutions that can handle larger inputs within a set period of time i.e. code with a faster run-time complexity. The locked stub code in the editor reads the following input from stdin and passes it to the function: The first line contains an integer, k, denoting the desired sum. The second line contains an integer, n, denoting the size of the array, a. Each line i of the n subsequent lines (where 0 lessthanorequalto i

## Expert Answer

This program requires nested loop inorder to find the pairs so complexity will be On2.

Please find below the solution and attached output:

Note : while pasting the code intendation (spacing) might be ommited as it is chegg limitation so please refer the attached code screenshot :

save below code as **pair.py** or any name needed please take care of itendation (spacing) as per python standard.

**def find_pair(k,a):**

**“””**

**This program will find the**

**number of pair equalivalent to sum k**

**“””**

**#initialize count variable with 0**

**count=0**

**#nested looping through array a**

**for i in range(0,len(a)):**

**for j in range(i+1,len(a)):**

**#if equal to sum**

**if a[i] + a[j] == k:**

**#uncomment below line if u want to seek pair with its value**

**#print(“Pair is {“+str(a[i])+”, “+str(a[j])+”}”)**

**#increasing the count**

**count = count + 1**

**return count**

**#end of function**

**#empty list / array**

**a=[]**

**#asking sum**

**k= int(input(“Enter the value of k (desired sum) : “))**

**#askinh no of elements in array**

**n=int(input(“Enter an no of elements in array : “))**

**#using loop scanning no in array**

**for i in range(0,n):**

**a.append(int(input()))**

**if __name__ == “__main__”:**

**#finding pair by calling function**

**no_of_pairs = find_pair(k,a);**

**print(“nNo of pairs : “+str(no_of_pairs))**

#Code screenshot:

#Code Output:

p