Java(javac 1.8) 解法, 执行用时: 195ms, 内存消耗: 21396K, 提交时间: 2021-04-13 08:52:14

import java.util.Scanner;

public class Main {
	public static int map[];
	public static boolean check(int x){
		for(int i=0;i<3;i++){
			if(map[i*3+0]+map[i*3+1]+map[i*3+2]==3*x
			||map[3*0+i]+map[3*1+i]+map[3*2+i]==3*x)return true;
		}
		return map[0]+map[4]+map[8]==3*x||map[2]+map[4]+map[6]==3*x;
	}
	public static int fine(int k){
		if(k>=10){
			return check(1)?1:check(-1)?-1:0;
		}else {
			int ping=0,shu=0,ying=0;
			int playr=k%2==1?1:-1;
			for(int i=0;i<9;i++){
				if(map[i]==0){
					map[i]=playr;
					if(check(playr))ying++;
					else {
						int test=fine(k+1);
						if(test==playr)ying++;
						else if(test==0)ping++;
						else shu++;
					}
					map[i]=0;
				}
			}
			return ying>0?playr:(ping>0?0:-playr);
		}
	}
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		int t=sc.nextInt();
		while(t-->0){
			int n=sc.nextInt();
			map=new int[9];
			for(int i=1;i<=n;i++){
				int x=sc.nextInt();
				int y=sc.nextInt();
				map[(x-1)*3+y-1]=i%2==1?1:-1;//X=1;O=-1;
			}
			int ans=fine(n+1);
			System.out.println(ans==1?"X":ans==-1?"O":"-1");
		}
	}
}

C++(clang++ 11.0.1) 解法, 执行用时: 18ms, 内存消耗: 424K, 提交时间: 2022-11-05 22:09:52

#include <bits/stdc++.h>
using namespace std;
int t,n,g[10];
int check(int u){
	if(g[0]+g[4]+g[8]==u*3||g[2]+g[4]+g[6]==u*3)return 1;
	if(g[0]+g[1]+g[2]==u*3||g[3]+g[4]+g[5]==u*3||g[6]+g[7]+g[8]==u*3)return 1;
	if(g[0]+g[3]+g[6]==u*3||g[1]+g[4]+g[7]==u*3||g[2]+g[5]+g[8]==u*3)return 1;
	return 0;
}
int dfs(int st){
	if(st==10){
		if(check(1))return 1;
		if(check(-1))return -1;
		return 0;
	}else{
		int win=0,lose=0,draw=0;
		int t=st&1?1:-1;
		for(int i=0;i<9;i++){
			if(!g[i]){
				g[i]=t;
				if(check(t))win++;
				else{
					int p=dfs(st+1);
					if(p==t)win++;
					else if(!p)draw++;
					else lose++;
				}g[i]=0;
			}
		}
		if(win)return t;
		if(draw) return 0;
		return -t;
	}
}
int main(){
	cin>>t;
	while(t--){
		for(int i=0;i<10;i++){
			g[i]=0;
		}
		cin>>n;
		for(int i=1;i<=n;i++){
			int x,y;
			cin>>x>>y;
			x--,y--;
			if(i%2==0)g[x*3+y]=-1;
			else g[x*3+y]=1;
		}int ans=dfs(n+1);
		if(ans==1)cout<<"X"<<endl;
		else if(ans==0)cout<<"-1"<<endl;
		else cout<<"O"<<endl;
	}
	return 0;
}