50、剑指offer--数组中重复数字

 1 class Solution {
 2 public:
 3     // Parameters:
 4     //        numbers:     an array of integers
 5     //        length:      the length of array numbers
 6     //        duplication: (Output) the duplicated number in the array number
 7     // Return value:       true if the input is valid, and there are some duplications in the array number
 8     //                     otherwise false
 9     bool duplicate(int numbers[], int length, int* duplication) {
10         if(length <= 0)
11             return false;
12         for(int i=0;i<length;i++)
13         {
14             if(numbers[i] <0 || numbers[i]>length-1)
15             {
16                 return false;
17             }
18         }
19         for(int i=0;i<length;i++)
20         {
21             while(numbers[i] != i)
22             {
23                 if(numbers[i] == numbers[numbers[i]])
24                 {
25                     *duplication = numbers[i];
26                     return true;
27                 }
28                 //交换
29                 int temp = numbers[i];
30                 numbers[i] = numbers[temp];
31                 numbers[temp] = temp;
32             }
33         }
34         return false;
35     }
36 };