Kth Missing Positive Number LeetCode solution in C++

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class Solution {
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 public:
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  int findKthPositive(vector<int> &arr, int k) {
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    int n = arr.size();
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    int low = 0, high = n - 1;
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    while (low <= high) {
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      int mid = (high - low) / 2 + low;
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      int x = arr[mid] - mid - 1; // will give no. of missing elements
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      if (x >= k)
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        high = mid - 1;
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      else
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        low = mid + 1;
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    }
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    return k + low;
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  }
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};