POJ 2311 Cutting Game(SG函数)

本文介绍了一款名为CuttingGame的游戏,该游戏在一个W*H网格的矩形纸上进行,玩家轮流切割纸张成两个矩形部分。文章通过深度优先搜索(DFS)计算Sprague-Grundy(SG)函数值来确定先手是否能赢得游戏。

 

Cutting Game

Time Limit: 1000MS Memory Limit: 65536K
Total Submissions: 4806 Accepted: 1760

Description

Urej loves to play various types of dull games. He usually asks other people to play with him. He says that playing those games can show his extraordinary wit. Recently Urej takes a great interest in a new game, and Erif Nezorf becomes the victim. To get away from suffering playing such a dull game, Erif Nezorf requests your help. The game uses a rectangular paper that consists of W*H grids. Two players cut the paper into two pieces of rectangular sections in turn. In each turn the player can cut either horizontally or vertically, keeping every grids unbroken. After N turns the paper will be broken into N+1 pieces, and in the later turn the players can choose any piece to cut. If one player cuts out a piece of paper with a single grid, he wins the game. If these two people are both quite clear, you should write a problem to tell whether the one who cut first can win or not.

Input

The input contains multiple test cases. Each test case contains only two integers W and H (2 <= W, H <= 200) in one line, which are the width and height of the original paper.

Output

For each test case, only one line should be printed. If the one who cut first can win the game, print "WIN", otherwise, print "LOSE".

Sample Input

2 2
3 2
4 2

Sample Output

LOSE
LOSE
WIN

 

分析

dfs求sg值。居然可以这样玩(⊙_⊙)

code

 1 #include<cstdio>
 2 #include<set>
 3 #include<cstring>
 4 
 5 using namespace std;
 6 int sg[500][500];
 7 
 8 
 9 int get_SG(int w,int h) {
10     if (sg[w][h] != -1) return sg[w][h];
11     set<int>s;
12     for (int i=2; w-i>=2; ++i) //竖直切
13         s.insert(get_SG(i,h)^get_SG(w-i,h));
14     for (int i=2; h-i>=2; ++i) //水平切
15         s.insert(get_SG(w,i)^get_SG(w,h-i));
16     for (int j=0; ; ++j) 
17         if (!s.count(j)) {sg[w][h] = j;break;}
18     return sg[w][h];
19 
20 }
21 int main () {
22     memset(sg,-1,sizeof(sg));
23     int w,h;
24     while (~scanf("%d%d",&w,&h)) {
25         if (get_SG(w,h)==0) puts("LOSE");
26         else puts("WIN");
27     }
28     return 0;
29 }

 

转载于:https://www.cnblogs.com/mjtcn/p/8481924.html

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