Make Sum Divisible by P LeetCode solution in C++

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class Solution {
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 public:
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  int minSubarray(vector<int> &nums, int p) {
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    int n = nums.size();
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    int sm = 0;
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    int ans = INT_MAX, cur = INT_MAX;
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    for (int it : nums) sm = (sm + it) % p;
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    if (sm == 0) return 0;
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    unordered_map<long long, int> mp = {{0, -1}};
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    long long pre = 0;
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    for (int i = 0; i < n; i++) {
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      pre = (pre + nums[i]) % p;
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      mp[pre] = i;
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      if (mp.count((pre - sm + p) % p) > 0) cur = i - mp[(pre - sm + p) % p];
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      ans = min(ans, cur);
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    }
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    if (ans == INT_MAX || ans == n)
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      return -1;
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    else
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      return ans;
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  }
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};