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
思路
- 用
map容器记录字符出现的次数，同时另开一个数组record记录输入的顺序 - 读完之后扫描
record，依次判断是否是unique的
代码
#include<bits/stdc++.h>
using namespace std;
int record[10010];
int len = 0;
int main()
{
int n;
scanf("%d", &n);
int t;
map<int,int> mp;
for(int i=0;i<n;i++)
{
scanf("%d", &t);
if(mp.count(t) == 0) //判断是否之前有出现过
{
record[len++] = t; //记录读进来的顺序
mp[t] = 1;
}else mp[t]++; //否则出现次数+1
}
for(int i=0;i<len;i++)
{
if(mp[record[i]] == 1)
{
printf("%d
", record[i]);
return 0;
}
}
printf("None
");
return 0;
}
引用
https://pintia.cn/problem-sets/994805342720868352/problems/994805444361437184