1497. Check If Array Pairs Are Divisible by k
Given an array of integers arr of even length n and an integer k.
We want to divide the array into exactly n / 2 pairs such that the sum of each pair is divisible by k.
Return true If you can find a way to do that or false otherwise.
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| class Solution {
public:
bool canArrange(vector<int>& arr, int k) {
unordered_map<int, int> freq;
for(auto& a : arr) {
freq[((a % k) + k) % k]++;
}
for(auto& [remainder, count] : freq) {
if(remainder == 0) {
if(count & 1) return false;
} else if(remainder * 2 == k) {
if(count & 1) return false;
} else {
if(freq[k - remainder] != count) return false;
}
}
return true;
}
};
|
