PAT 1041 Be Unique (20)

#include<iostream>

#include<cstdio>

#include<string>

#include<cstring>

#include<queue>

#include<vector>

#include<cmath>

#include<iomanip>

#include<algorithm>

using namespace std;



const int SIZE = 100000+5;

int arrCount[SIZE];



int main()

{

	int N,i,x;

	vector<int> v;

	memset(arrCount,0,sizeof(arrCount));

//	cin>>N;

	scanf("%d",&N);

	for(i=0; i<N; i++)

	{

		scanf("%d",&x);

	//	cin>>x;

		arrCount[x]++;

		v.push_back(x);

	}

	for(i=0; i<v.size(); i++)

		if(arrCount[v[i]] == 1)

		{

			cout<<v[i]<<endl;

			break;

		}

	if(i == v.size())

		cout<<"None"<<endl;

	return 0;

}