题意

n个数, 统计1-n中未出现的数

方法

遍历和标记

代码

class Solution {
public:
    vector<int> findDisappearedNumbers(vector<int>& nums) {
        sort(nums.begin(), nums.end());

        int n = nums.size();
        vector<int> ans;
        vector<int> num(100024);
        for (int i = 0; i <= n; i++) {
            num[i] = 0;
        }

        for (int i = 0; i < n; i++) {
            num[nums[i]] = 1;
        }

        for (int i = 1; i <= n; i++) {
            if (num[i] == 0) ans.push_back(i);
        }

        return ans;
    }
};