find pairs in array whose sum is already present.txt

Find pairs in array whose sum is already present
Given an array A of N distinct and positive elements, the task is to find number of unordered pairs whose sum already exists in given array.

Expected Complexity : n^2

CONSTRAINTS

1 <= N <= 1000
1 <= A[i] <= 10^6 + 5
SAMPLE INPUT

A : [ 3, 4, 2, 6 ,7]
SAMPLE OUTPUT

2
EXPLANATION

The pairs following the conditions are : 
(2,4) = 6,
(3,4) = 7


int Solution::solve(vector<int> &A) {
    int n=A.size();
    int hash[3000000];
    memset(hash,false,sizeof(hash));
    for(int i=0;i<n;i++)
    hash[A[i]]=true;
    int ct=0;
    for(int i=0;i<n;i++){
        for(int j=i+1;j<n;j++){
            if(hash[A[i]+A[j]])
            ct++;
        }
    }
    return ct;
    
}