[LeetCode] First Missing Positive

 1 class Solution {
 2 public:
 3     int firstMissingPositive(vector<int>& nums) {
 4         int n = nums.size();
 5         for (int i = 0; i < n; i++)
 6             while (nums[i] > 0 && nums[i] <= n && nums[nums[i] - 1] != nums[i])
 7                 swap(nums[i], nums[nums[i] - 1]);
 8         for (int i = 0; i < n; i++)
 9             if (nums[i] != i + 1)
10                 return i + 1;
11         return n + 1;
12     }
13 };