[jzof-03] repeated numbers in the array

 Find the repeated numbers in the array .


 At a length of  n  Array of  nums  All the numbers in  0～n-1  Within the scope of . Some numbers in the array are repeated , But I don't know how many numbers are repeated , I don't know how many times each number has been repeated . Please find any duplicate number in the array .

 Input ：
[2, 3, 1, 0, 2, 5, 3]
 Output ：2  or  3 

Train of thought ： Traverse + Use Set aggregate

Train of thought two ： Replacement in place .

import java.util.*;

public class Solution {
    
    /** *  The class name in the code 、 Method name 、 The parameter name has been specified , Do not modify , Return the value specified by the method directly  * * * @param numbers int Integer one-dimensional array  * @return int integer  */
    public int duplicate (int[] numbers) {
    
        int i = 0;
        while (i < numbers.length) {
    
            if (numbers[i] == i) {
    
                i++;
                continue;
            }
            if (numbers[numbers[i]] == numbers[i]) {
    
                return numbers[i];
            }
            int temp = numbers[i];
            numbers[i] = numbers[temp];
            numbers[temp] = temp;
        }
        return -1;
    }
}