Count pairs with given sum

Problem Link: https://practice.geeksforgeeks.org/problems/count-pairs-with-given-sum5022/1

class Solution:
    def getPairsCount(self, arr, n, k):
        # code here
        double_sum=0
        d={}
        for i in arr:
            if(i not in d):
                d[i]=1
            else:
                d[i]+=1
        
        for i in arr:
            if(k-i in d):
                double_sum=double_sum+d[k-i]
                
            # Case : arr[i]+arr[i]=k
            # This case must be ignored
            if(i==k-i):
                double_sum=double_sum-1
        
        return double_sum//2