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]. 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 (≤) 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
题解:
用一个flag数组存储每个数字出现的次数,输出第一个次数为1的那一位,没有则输出None
注意:两层for循环会运行超时!
#include<bits/stdc++.h> using namespace std; const int maxn=100010; int main(){ vector<int> v; int flag[maxn]; fill(flag,flag+maxn,0); int n,m; scanf("%d",&n); for(int i=0;i<n;i++){ scanf("%d",&m); v.push_back(m); flag[m]++; } for(int i=0;i<v.size();i++){ if(flag[v[i]]==1){ printf("%d ",v[i]); return 0; } } printf("None "); return 0; }