剑指offer-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) {
        if(length==0){
            return false;
        }
        int cop[length];
        for(int i=0;i<length;i++){
            cop[i] = 0;
        }
        for(int i=0;i<length;i++){
            int temp = numbers[i];
            cop[temp]++;
        }
        for(int i=0;i<length;i++){
            if(cop[numbers[i]]>=2){
                duplication[0] = numbers[i];
                return true;
            }
            
        }
        return false;
    }
};