leetcode-----41. 缺失的第一个正数

• 链接：https://leetcode-cn.com/problems/first-missing-positive/

代码

class Solution {
public:
    int firstMissingPositive(vector<int>& nums) {
        int n = nums.size();
        if (n == 0) return 1;

        for (int i = 0; i < n; ++i) {
            while (nums[i] > 0 && nums[i] < n && nums[i] != nums[nums[i]]) {
                swap(nums[i], nums[nums[i]]);
            }
        }
        for (int i = 1; i < n; ++i) {
            if (nums[i] != i) return i;
        }
        return nums[0] == n ? n + 1 : n;
    }
};