BZOJ 1982: [Spoj 2021]Moving Pebbles [博弈论 对称]

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
using namespace std;
typedef long long ll;
const int N=1e5+5;
inline int read(){
    char c=getchar();int x=0,f=1;
    while(c<‘0‘||c>‘9‘){if(c==‘-‘)f=-1;c=getchar();}
    while(c>=‘0‘&&c<=‘9‘){x=x*10+c-‘0‘;c=getchar();}
    return x*f;
}
 
int n,a[N];
int main(){
    n=read();
    if(n&1) puts("first player");
    else{
        for(int i=1;i<=n;i++) a[i]=read();
        sort(a+1,a+1+n);
        int flag=0;
        for(int i=2;i<=n;i+=2) if(a[i]!=a[i-1]) {flag=1;break;}
        puts(flag ? "first player" : "second player");
    }
}