Leetcode 41 Solution

This article provides solution to leetcode question 41 (first-missing-positive).
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https://leetcode.com/problems/first-missing-positive

Solution

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