#include <bits/stdc++.h>
using namespace std;
int countKDifference(vector<int>& nums, int k) {
int n = nums.size();
unordered_map<int, int> freq;
for (int i : nums){
freq[i]++;
}
int count = 0;
for (int i : nums){
if(freq[i+k] > 0){
count += (freq[i] * freq[i+k]);
}
if(freq[i-k] > 0){
count += (freq[i] * freq[i-k]);
}
freq[i] = 0;
}
return count;
}
int main() {
// your code goes here
vector<int> nums = {1, 3};
cout << countKDifference(nums, 3);
return 0;
}
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