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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.
class Solution { public: int firstMissingPositive(int A[], int n) { if(A==NULL||n<1)return 1; int i; for (i=0;i<n;i++) { if (A[i]>0&&A[i]!=i+1&&A[i]<=n&&A[i]!=A[A[i]-1]) { int temp=A[i]; A[i]=A[A[i]-1]; A[temp-1]=temp; i--; } } for (i=0;i<n;i++) { if (A[i]!=i+1) return i+1; } return i+1; } };
leetcode[41]First Missing Positive
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原文地址：http://www.cnblogs.com/Vae98Scilence/p/4283577.html
