【剑指offer】数组中重复的数字

 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)    return false;
11         if(length == 1){
12             *duplication = numbers[0];
13             return false;
14         }
15         set<int> ss;
16         for(int i = 0 ;i < length; i++){
17             if(ss.count(numbers[i])){
18                 *duplication = numbers[i];
19                 return true;
20             }
21             else    ss.insert(numbers[i]);
22         }
23         return false;
24     }
25 };