剑指offer——数组中重复的数字

solution：

std：

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) {
        set<int> s;
        bool flag = false ;
        for(int i=0;i<length;i++){
            int siz1 = s.size();
            s.insert(numbers[i]);
            int siz2 = s.size();
            if(siz1 == siz2){
                duplication[0] = numbers[i];
                flag = true;
                break ;
            }
        }
        return flag ;
    }
};