Leet Code Daily 2024-06-09 - Subarray Sums Divisible by K

class Solution {
public:
    int subarraysDivByK(vector<int>& nums, int k) {
        unordered_map<int, int> cnt;
        cnt[0] = 1;
        int sum = 0, ans = 0;
        for (const auto& x : nums) {
            sum = (sum + x) % k;
            sum = (sum + k) % k;
            ans += cnt[sum];
            cnt[sum]++;
        }
        return ans;
    }
};