题解 | #数组中重复的数字#

#include <fstream>
class Solution {
public:
    int duplicate(vector<int>& numbers) {
        int n = numbers.size();
        if(n<1) return -1;
        for(int i = 0;i<n;i++){
            while (numbers[i]!=i) {
                if(numbers[i]==numbers[numbers[i]]){
                    return numbers[i];
                }
                swap(numbers[i], numbers[numbers[i]]);
            }
        }
        return -1;
    }
};