1041. Be Unique (20)

​ 时间限制

​ 100 ms

​ 内存限制

​ 65536 kB

​ 代码长度限制

​ 16000 B

​ 判题程序

​ Standard

​ 作者

​ CHEN, Yue

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.

Sample Input 1:

7 5 31 5 88 67 88 17

Sample Output 1:

31

Sample Input 2:

5 888 666 666 888 888

Sample Output 2:

None

代码如下：

由于时间限制为100ms,所以就要注意时间复杂度了，如果时间复杂度为O(n^2)的应该是不行了，我下面是用的用一个vector存输入的数，一个vector用于计数，

若是数==1，则独一无二，输出第一个即可

#include<cstdio>
#include<vector>
using namespace std;
int main(){
	int n;
	scanf("%d",&n);
	vector<int> vec(100001,0);
	vector<int> vec1;
	int num;
	for(int i=0;i<n;++i){
		scanf("%d",&num);
		++vec[num];
		vec1.push_back(num);
	}
	int flag=0;
	for(int i=0;i<vec1.size();++i){
		if(vec[vec1[i]]==1){
			flag=1;
			printf("%d",vec1[i]);
			return 0;
		}
	}
	if(flag==0){
		printf("None");
	}
	return 0;
}