PAT Advanced 1041 Be Unique (20分)
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
这题理解题意后是简单题,主要考察了哈希映射。
找出数字只出现一次的数。
#include <iostream> using namespace std; int m[10000] = {0}; int main(){ int N; cin >> N; int arr[N]; for(int i = 0; i < N; i++){ cin >> arr[i]; m[arr[i]]++; } for(int i = 0; i < N; i++){ if(m[arr[i]] == 1){ cout << arr[i]; return 0; } } cout << "None"; return 0; }