Poj 1085 Triangle War (极大极小搜索)

 

 题目链接：http://poj.org/problem?id=1085

 

题意：两个人轮流在九个小正三角形组成的大三角形上面选取边，如果当前选择的边刚好为某些三角形最后一个未选取的边，则该玩家得分为这些三解形数目，如果当前玩家取

得三角形，则可以得到另一个机会选择。

 

Min_MAX + alpha_beta剪枝

Code:

#include<stdio.h>#include<stdlib.h>#include<string.h>#include<time.h>#define M 11int map[M][M]={{0,0,0,0,0,0,0,0,0,0,0},{0,0,0,1,0,0,0,0,0,0,0},{0,0,0,2,3,4,0,0,0,0,0},{0,1,2,0,0,5,6,0,0,0,0},{0,0,3,0,0,7,0,9,10,0,0},{0,0,4,5,7,0,8,0,11,12,0},{0,0,0,6,0,8,0,0,0,13,14},{0,0,0,0,9,0,0,0,15,0,0},{0,0,0,0,10,11,0,15,0,16,0},{0,0,0,0,0,12,13,0,16,0,17},{0,0,0,0,0,0,0,14,0,17,0}};int tri[9]={7,152,52,352,34304,3200,71680,12544,155648};/*tri[0]=1|(1<<1)|(1<<2);tri[1]=(1<<3)|(1<<4)|(1<<7);tri[2]=(1<<2)|(1<<4)|(1<<5);tri[3]=(1<<5)|(1<<6)|(1<<8);tri[4]=(1<<9)|(1<<10)|(1<<15);tri[5]=(1<<7)|(1<<10)|(1<<11);tri[6]=(1<<11)|(1<<12)|(1<<16);tri[7]=(1<<8)|(1<<12)|(1<<13);tri[8]=(1<<13)|(1<<14)|(1<<17);*/const int mirror=(1<<18)-1;int MinSearch(int ,int ,int ,int );int MaxSearch(int ,int ,int ,int );int Place(int s,int seg,int &of){int i;int r=s|seg;for(i=0;i<9;i++){if(((tri[i]&s)!=tri[i])&&((tri[i]&r)==tri[i]))of++;}return r;}int MaxSearch(int statu,int alpha,int as,int bs){int bit,seg;int cs,r;int max=-1,tmp;if(as>=5) return 1;if(bs>=5) return -1;if(statu==mirror)return as>bs?1:-1;bit=(~statu)&mirror;while(bit){seg=bit&(-bit);cs=as;r=Place(statu,seg,cs);if(cs>as)tmp=MaxSearch(r,alpha,cs,bs);elsetmp=MinSearch(r,max,cs,bs);if(tmp>max) max=tmp;if(max>=alpha)return max;bit-=seg;}return max;}int MinSearch(int statu,int beta,int as,int bs){int bit,seg,cs,r;int min=1,tmp;if(as>=5) return 1;if(bs>=5) return -1;if(statu==mirror)return as>bs?1:-1;bit=(~statu)&mirror;while(bit){seg=bit&(-bit);cs=bs;r=Place(statu,seg,cs);if(cs>bs)tmp=MinSearch(r,beta,as,cs);elsetmp=MaxSearch(r,min,as,cs);if(tmp<min) min=tmp;if(tmp<=beta) return min;bit-=seg;}return min;}int main(){int t,k=0;int a,b,n,i,turn;int res;int ofa,ofb;int ta,tb;int status;scanf("%d",&t);while(t--){scanf("%d",&n);status=ofa=ofb=0;for(turn=i=0;i<n;i++){scanf("%d%d",&a,&b);ta=ofa,tb=ofb;status=Place(status,1<<map[a][b],(turn&1)?ofb:ofa);if(ta==ofa&&tb==ofb)turn++;}if(turn&1)res=MinSearch(status,-1,ofa,ofb);elseres=MaxSearch(status,1,ofa,ofb);printf("Game %d: %c wins.\n",++k,res==1?'A':'B');}return 0;}