题目描述

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

代码实现

本题比较简单，hash后遍历即可（注意一下需要“首先”满足条件的数）

AC代码

  1. #include <iostream>
  2. using namespace std;
  3. int main()
  4. {
  5.     int number[10001] = {0}, N;
  6.     cin >> N;
  7.     int bets[N];
  8.     for (int i = 0; i < N; i++)
  9.     {
  10.         cin >> bets[i];
  11.         number[bets[i]]++;
  12.     }
  13.     for (int i = 0; i < N; i++)
  14.     {
  15.         if (number[bets[i]] == 1)
  16.         {
  17.             cout << bets[i] << endl;
  18.             return 0;
  19.         }
  20.     }
  21.     cout << "None" << endl;
  22.     return 0;
  23. }