leetcode_missing_number

发表于

难度：Easy

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class Solution {
public:
    int missingNumber(vector<int>& nums) {
        int n = nums.size();
        int sum = n*(n+1)/2;
        for(int i = 0; i< nums.size();i++)
        {
            sum -= nums[i];
        }
        return sum;
    }
};

26ms,95.34%

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class Solution {
public:
    int missingNumber(vector<int>& nums) {
        vector<int> ret (nums.size()+1,0);
        for(int i = 0; i < nums.size(); i++)
        {
            ret[nums[i]] = 1;
        }
        for(int i = 0; i < ret.size();i++)
        {
            if(ret[i] == 0)
                return i;
        }
        return 0;
    }
};

29ms，53.88%