剑指offerJZ50 数组中重复的数字

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) {
        int i = 0,j;
        for(i;i<length;i++){
            for(j=i+1;j<length;j++){
                if(numbers[i] == numbers[j]){
                    *duplication = numbers[i];
                    return numbers[i];
                }
            }
        }
        return 0;
    }
};