1041. Be Unique (20)

Being unique is so important to people on Mars that even their lottery is designed in a unique way. The rule of winning is simple: one bets on a number chosen from [1, 104]. The first one who bets on a unique number wins. For example, if there are 7 people betting on 5 31 5 88 67 88 17, then the second one who bets on 31 wins.

Input Specification:

Each input file contains one test case. Each case contains a line which begins with a positive integer N (<=105) and then followed by N bets. The numbers are separated by a space.

Output Specification:

For each test case, print the winning number in a line. If there is no winner, print "None" instead.

IDEA

1.如果是一遍输入数据，一遍找是否已经存在（遍历，或find_if函数）会超时；

2.提出说bets在[1, 10000]之间，所以可以用一个数组存，数组的下标就是bets

CODE

#include<iostream>
using namespace std;
int main(){
	int n;
	cin>>n;
	int num[100002];
	int count[10002]={0};
	for(int i=0;i<n;i++){
		cin>>num[i];
		count[num[i]]++;
	}
	for(int i=0;i<n;i++){
		if(count[num[i]]==1){
			cout<<num[i];
			return 0;
		}
	}
	cout<<"None";
	return 0;
}