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  • PTA(Advanced Level)1041.Be Unique

    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
    • 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
    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

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  • 原文地址:https://www.cnblogs.com/MartinLwx/p/11896245.html
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