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.
Solution:
class Solution {
public:
int firstMissingPositive(vector<int>& nums) {
for(int i=0; i<nums.size(); i++){
if(i+1==nums[i]) continue;
int x = nums[i];
while(x>=1 && x<=nums.size() && x!=nums[x-1]){
swap(x, nums[x-1]);
}
}
for(int i=0; i<nums.size(); i++){
if(i+1!=nums[i]) return i+1;
}
return nums.size()+1;
}
};
41. First Missing Positive(C++)
原文：http://www.cnblogs.com/devin-guwz/p/6731035.html