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path: root/kth_smallest_sorted_matrix.cpp
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#include "leetcode.h"

class Solution {
public:
  int kthSmallest(vector<vector<int>> &matrix, int k) {
    int n = matrix.size(), left = matrix[0][0], right = matrix[n - 1][n - 1],
        mid = 0;
    while (left < right) {
      mid = left + (right - left) / 2;
      int num = 0;
      for (int i = 0; i < n; i++) {
        int pos = upper_bound(matrix[i].begin(), matrix[i].end(), mid) -
                  matrix[i].begin();
        num += pos;
      }
      if (num < k)
        left = mid + 1;
      else
        right = mid;
    }
    return left;
  }
};

int main() {
  Solution obj;
  vector<vector<int>> matrix;
  int k;
  obj.kthSmallest(matrix, k);
}