LeetCode 448. 找到所有数组中消失的数字

题目链接：点击这里

class Solution {
public:
    vector findDisappearedNumbers(vector& nums) {
        int n = nums.size();
        for(int i = 0; i < n; i++)
        {
            int x = abs(nums[i]);
            if(nums[x - 1] > 0)
                nums[x - 1] *= -1;
        }

        vector ans;
        for(int i = 0; i < n; i++)
            if(nums[i] > 0)
                ans.push_back(i + 1);
        return ans;
    }
};