// 1539. Kth Missing Positive Number #include "leetcode.h" /* * given array 'arr' of positive integers sorted in a strictly increasing order, * and an integer 'k', return 'kth' positive integer missing from array -- o(log * n) */ class Solution { public: int findKthPositive(vector &arr, int k) { int l = 0, r = arr.size(), m; while (l < r) { m = (l + r) / 2; if (arr[m] - 1 - m < k) l = m + 1; else r = m; } return l + k; } }; int main() { Solution obj; vector a1 = {2, 3, 4, 7, 11}, a2 = {1, 2, 3, 4}; cout << obj.findKthPositive(a1, 5) << endl; // expect: 9 cout << obj.findKthPositive(a2, 2) << endl; // expect: 6 }