C++/代码：

C++/代码

class Solution {
public:
    // Parameters:
    //        numbers:     an array of integers
    //        length:      the length of array numbers
    //        duplication: (Output) the duplicated number in the array number
    // Return value:       true if the input is valid, and there are some duplications in the array number
    //                     otherwise false
    bool duplicate(int numbers[], int length, int* duplication) {
        if(numbers == NULL || length==0) return false;
        for(int i = 0;i < length;i ++){
            if(numbers[i] <= 0 || numbers[i] >= length) return false;
        }
        for(int i = 0;i < length;i ++){
            while(numbers[i] != i && numbers[i] != numbers[numbers[i]]) swap(numbers[i],numbers[numbers[i]]);
            if(numbers[i] != i && numbers[i] == numbers[numbers[i]]) {
                *duplication = numbers[i];
                break;
            }
        }
        return true;
    }
};