Make equal elements Array

• Time : $O(n)$
• Space : $O(n)$

int Solution::solve(vector<int> &A, int B) {
    unordered_map<int, int> freq;
    for(int i = 0; i < A.size(); i++) {
        int sub = A[i] - B, add = A[i] + B, none = A[i];
        freq[sub] += 1;
        freq[add] += 1;
        freq[none] += 1;
        if(freq[sub] != i + 1 and freq[add] != i + 1 and freq[none] != i + 1) return 0;
    }
    return 1;
}