First Missing Positive

<-H 41> First Missing Positive

class Solution {
public:
    int firstMissingPositive(vector<int>& nums) {
        for(int i = 0; i != nums.size(); i++) {
            while(nums[i] != (i + 1)) {
                if (nums[i] <= 0 || nums[i] > nums.size() || nums[i] == nums[nums[i] - 1])
                    break;
                swap(nums[i], nums[nums[i] - 1]);
            }
        }

        for(int i = 0; i != nums.size(); i++)
            if(nums[i] != (i + 1))
                return i + 1;
        return nums.size() + 1;
    }
};