数组中重复的数字

 1 public class Solution {
 2     // Parameters:
 3     //    numbers:     an array of integers
 4     //    length:      the length of array numbers
 5     //    duplication: (Output) the duplicated number in the array number,length of duplication array is 1,so using duplication[0] = ? in implementation;
 6     //                  Here duplication like pointor in C/C++, duplication[0] equal *duplication in C/C++
 7     //    这里要特别注意~返回任意重复的一个，赋值duplication[0]
 8     // Return value:       true if the input is valid, and there are some duplications in the array number
 9     //                     otherwise false
10     public boolean duplicate(int numbers[],int length,int [] duplication) {
11         int i = 0;
12         while (i < length) {
13             if (numbers[i] == numbers[ numbers[i]] && i != numbers[i]) {
14                 duplication[0] = numbers[i];
15                 return true;
16             } else if (i != numbers[i] && numbers[i] != numbers[ numbers[i]]){
17                 int temp = numbers[i];
18                 numbers[i] = numbers[ numbers[i]];
19                 numbers[ temp ] = temp;
20             } else {
21                 i++;
22             }
23         }
24         
25         duplication[0] = -1;
26         return false;
27     }
28 }