C++ 代码

class Solution {
public:
    int duplicateInArray(vector<int>& nums) {
        int n = nums.size();
        int num[n+1] = {0};
        for(int i = 0; i < n; i++)
        {
            num[nums[i]]++;
        }
        for(int j = 0; j < n; j++)
        {
            if(num[j] != 0 && num[j] != 1)
                return j;
        }
    }
};