hdu 1175——連連看

深搜+剪枝

#include<iostream>#include<cstdio>using namespace std;int map[1010][1010];int dir[4][2]={-1,0,1,0,0,-1,0,1};// 上下 左右  int flag;int n,m;int x1,x2,y1,y2; void dfs(int x,int y,int k,int d){int i,j;int temp;if(flag)return ;if(x==x2&&y==y2){printf("YES\n");flag=1;return ;}if(map[x][y]==0&&x<n&&y<m&&x>=0&&y>=0&&k<=2){if(k==0){if(d==0||d==1){if(y2-y<0){temp=map[x][y];map[x][y]=-1;dfs(x+dir[2][0],y+dir[2][1],k+1,2);map[x][y]=temp;}if(y2-y>0){temp=map[x][y];map[x][y]=-1;dfs(x+dir[3][0],y+dir[3][1],k+1,3);map[x][y]=temp;}if(y2==y){if((x2-x<0&&d==1)||(x2-x>0&&d==0))return ;else{temp=map[x][y];map[x][y]=-1;dfs(x+dir[d][0],y+dir[d][1],k,d);map[x][y]=temp;}}}if(d==2||d==3){if(x2-x<0){temp=map[x][y];map[x][y]=-1;dfs(x+dir[0][0],y+dir[0][1],k+1,0);map[x][y]=temp;}if(x2-x>0){temp=map[x][y];map[x][y]=-1;dfs(x+dir[1][0],y+dir[1][1],k+1,1);map[x][y]=temp;}if(x2==x){if(y2-y<0&&d==3||y2-y>0&&d==2)return ;else{temp=map[x][y];map[x][y]=-1;dfs(x+dir[d][0],y+dir[d][1],k,d);map[x][y]=temp;}}}temp=map[x][y];map[x][y]=-1;dfs(x+dir[d][0],y+dir[d][1],k,d);map[x][y]=temp;}if(k==1){if(d==0||d==1){while(x!=x2){if(map[x][y]!=0)return ;x=x+dir[d][0];y=y+dir[d][1];}if(y2-y>0){while(y!=y2){if(map[x][y]!=0)return ;x=x+dir[3][0];y=y+dir[3][1];}}if(y2-y<0){while(y!=y2){if(map[x][y]!=0)return ;x=x+dir[2][0];y=y+dir[2][1];}}if(y2==y){printf("YES\n");flag=1;return ;}}if(d==2||d==3){while(y!=y2){if(map[x][y]!=0)return ;x=x+dir[d][0];y=y+dir[d][1];}if(x2-x>0){while(x!=x2){if(map[x][y]!=0)return ;x=x+dir[1][0];y=y+dir[1][1];}}if(x2-x<0){while(x!=x2){if(map[x][y]!=0)return ;x=x+dir[0][0];y=y+dir[0][1];}}if(y2==y){printf("YES\n");flag=1;return ;}}}}}int main(){int i,j;int q;while(~scanf("%d%d",&n,&m)&&n+m){for(i=0;i<n;i++)for(j=0;j<m;j++)scanf("%d",&map[i][j]);scanf("%d",&q);for(i=0;i<q;i++){flag=0;scanf("%d%d%d%d",&x1,&y1,&x2,&y2);x1--;x2--;y1--;y2--;if(map[x1][y1]==map[x2][y2]&&map[x1][y1]!=0&&map[x2][y2]!=0){for(j=0;j<4;j++)dfs(x1+dir[j][0],y1+dir[j][1],0,j);//i代表方向 if(!flag)printf("NO\n");}elseprintf("NO\n");}}return 0;}