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题目要求：First Missing Positive
Given an unsorted integer array, find the first missing positive integer.
For example,
Given [1,2,0] return 3,
and [3,4,-1,1] return 2.
Your algorithm should run in O(n) time and uses constant space.
代码如下：
class Solution { public: int firstMissingPositive(int A[], int n) { for (int i = 0, temp = -1; i < n; i++) { while (A[i] - 1 >= 0 && A[i] - 1 < n && A[i] - 1 != i) { swap(A, i, A[i] - 1); if (A[i] == temp) { break; } else { temp = A[i]; } } } for (int i = 0; i < n; i++) { if (A[i] - 1 != i) { return i + 1; } } return n + 1; } private: void swap(int A[], int idx1, int idx2) { A[idx1] ^= A[idx2]; A[idx2] ^= A[idx1]; A[idx1] ^= A[idx2]; } };
LeetCode 041 First Missing Positive
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原文地址：http://www.cnblogs.com/510602159-Yano/p/4279247.html
