剑指offer——数组中重复的数字

#include <iostream>
#include <map>
#include <set>
using namespace 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
        int Find(int numbers[], int length,int num){
            int index = -1;
            for(int i = 0 ; i < length ; i++){
                if(numbers[i] == num){
                    index = i;
                    break;
                }
            }
            return index;
        }

        bool duplicate(int numbers[], int length, int* duplication) {
            if(length <= 0 || numbers ==NULL){
                return false;
            }
            map<int,int> Map;
            set<int> s;
            for(int i = 0 ; i < length ; i++){
                if(Map[numbers[i]] == 0){
                    Map[numbers[i]]++;
                }else if(Map[numbers[i]] >= 1){
                    s.insert(numbers[i]);
                    Map[numbers[i]]++;
                }
            }
            set<int>::iterator it;
            int cnt = 0;
            for(it = s.begin(); it != s.end() ; it++){
                if(Map[*it] > 1){
                    duplication[cnt++] = *it;
                    return true;
                }
            }
            return false; 
        }
};