PAT 甲级 1041 Be Unique （20 分）

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 [1,10​4​​]. 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 (≤10​5​​) 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

#include<iostream>
#include<map>

using namespace std;

int main()
{
    int N, temp, index = 1, min = 999999;
    map<int, int> m;

    cin >> N;

    for (int i = 0; i<N; ++i)
    {
        cin >> temp;

        if (m.find(temp) == m.end())
            m.insert(pair<int, int>(temp, index++));
        else
            m[temp] = 0;
    }

    map<int, int>::iterator begin = m.begin(), end = m.end(), i, minIndex;

    for (i = begin; i != end; ++i)
    {
        if (i->second>0 && i->second<min)
        {
            min = i->second;
            minIndex = i;
        }
    }

    if (min == 999999)
        cout << "None" << endl;
    else
        cout << minIndex->first << endl;
}