水题。不解释代码很长比较麻烦,我只会深搜,假期才看广搜。
#include<iostream>
using namespace std;
char map[5][5];
int mini,flag;
void dfs(int x,int count)
{
if(x==16)
{
int black,white;
black=0;
white=0;
for(int i=0;i<4;i++)
for(int j=0;j<4;j++)
if(map[i][j]=='b')
black=black+1;
else white=white+1;
if(black==16||white==16)
{
if(count<mini)
mini=count;
flag=1;
}
return;
}
int heng,zong;
char w,n,s,e,t;
heng=x/4;
zong=x%4;
if(heng==0&&zong==0)
{
t=map[heng][zong];
s=map[heng+1][zong];
e=map[heng][zong+1];
if(map[heng][zong]=='w')
map[heng][zong]='b';
else map[heng][zong]='w';
if(map[heng+1][zong]=='w')
map[heng+1][zong]='b';
else map[heng+1][zong]='w';
if(map[heng][zong+1]=='w')
map[heng][zong+1]='b';
else map[heng][zong+1]='w';
dfs(x+1,count+1);
map[heng][zong]=t;
map[heng+1][zong]=s;
map[heng][zong+1]=e;
}
else if(heng==0&&zong==3)
{
t=map[heng][zong];
w=map[heng][zong-1];
s=map[heng+1][zong];
if(map[heng][zong]=='b')
map[heng][zong]='w';
else map[heng][zong]='b';
if(map[heng][zong-1]=='w')
map[heng][zong-1]='b';
else map[heng][zong-1]='w';
if(map[heng+1][zong]=='w')
map[heng+1][zong]='b';
else map[heng+1][zong]='w';
dfs(x+1,count+1);
map[heng][zong]=t;
map[heng][zong-1]=w;
map[heng+1][zong]=s;
}
else if(heng==3&&zong==0)
{
t=map[heng][zong];
n=map[heng-1][zong];
e=map[heng][zong+1];
if(map[heng][zong]=='b')
map[heng][zong]='w';
else map[heng][zong]='b';
if(map[heng-1][zong]=='b')
map[heng-1][zong]='w';
else map[heng-1][zong]='b';
if(map[heng][zong+1]=='b')
map[heng][zong+1]='w';
else map[heng][zong+1]='b';
dfs(x+1,count+1);
map[heng][zong]=t;
map[heng-1][zong]=n;
map[heng][zong+1]=e;
}
else if(heng==3&&zong==3)
{
t=map[heng][zong];
n=map[heng-1][zong];
w=map[heng][zong-1];
if(map[heng][zong]=='b')
map[heng][zong]='w';
else map[heng][zong]='b';
if(map[heng-1][zong]=='b')
map[heng-1][zong]='w';
else map[heng-1][zong]='b';
if(map[heng][zong-1]=='b')
map[heng][zong-1]='w';
else map[heng][zong-1]='b';
dfs(x+1,count+1);
map[heng][zong]=t;
map[heng-1][zong]=n;
map[heng][zong-1]=w;
}
else if(heng==0&&zong>0&&zong<3)
{
w=map[heng][zong-1];
e=map[heng][zong+1];
s=map[heng+1][zong];
t=map[heng][zong];
if(map[heng][zong]=='b')
map[heng][zong]='w';
else map[heng][zong]='b';
if(map[heng][zong-1]=='b')
map[heng][zong-1]='w';
else map[heng][zong-1]='b';
if(map[heng][zong+1]=='b')
map[heng][zong+1]='w';
else map[heng][zong+1]='b';
if(map[heng+1][zong]=='b')
map[heng+1][zong]='w';
else map[heng+1][zong]='b';
dfs(x+1,count+1);
map[heng][zong-1]=w;
map[heng][zong+1]=e;
map[heng+1][zong]=s;
map[heng][zong]=t;
}
else if(heng>0&&zong==0&&heng<3)
{
t=map[heng][zong];
n=map[heng-1][zong];
s=map[heng+1][zong];
e=map[heng][zong+1];
if(map[heng][zong]=='b')
map[heng][zong]='w';
else map[heng][zong]='b';
if(map[heng-1][zong]=='b')
map[heng-1][zong]='w';
else map[heng-1][zong]='b';
if(map[heng+1][zong]=='b')
map[heng+1][zong]='w';
else map[heng+1][zong]='b';
if(map[heng][zong+1]=='b')
map[heng][zong+1]='w';
else map[heng][zong+1]='b';
dfs(x+1,count+1);
map[heng][zong]=t;
map[heng-1][zong]=n;
map[heng+1][zong]=s;
map[heng][zong+1]=e;
}
else if(zong==3&&heng>0&&heng<3)
{
t=map[heng][zong];
n=map[heng-1][zong];
s=map[heng+1][zong];
w=map[heng][zong-1];
if(map[heng][zong]=='b')
map[heng][zong]='w';
else map[heng][zong]='b';
if(map[heng-1][zong]=='b')
map[heng-1][zong]='w';
else map[heng-1][zong]='b';
if(map[heng+1][zong]=='b')
map[heng+1][zong]='w';
else map[heng+1][zong]='b';
if(map[heng][zong-1]=='b')
map[heng][zong-1]='w';
else map[heng][zong-1]='b';
dfs(x+1,count+1);
map[heng][zong]=t;
map[heng-1][zong]=n;
map[heng+1][zong]=s;
map[heng][zong-1]=w;
}
else if(heng==3&&zong>0&&zong<3)
{
t=map[heng][zong];
w=map[heng][zong-1];
e=map[heng][zong+1];
n=map[heng-1][zong];
if(map[heng][zong]=='b')
map[heng][zong]='w';
else map[heng][zong]='b';
if(map[heng][zong-1]=='b')
map[heng][zong-1]='w';
else map[heng][zong-1]='b';
if(map[heng][zong+1]=='b')
map[heng][zong+1]='w';
else map[heng][zong+1]='b';
if(map[heng-1][zong]=='b')
map[heng-1][zong]='w';
else map[heng-1][zong]='b';
dfs(x+1,count+1);
map[heng][zong]=t;
map[heng][zong-1]=w;
map[heng][zong+1]=e;
map[heng-1][zong]=n;
}
else {
t=map[heng][zong];
n=map[heng-1][zong];
s=map[heng+1][zong];
w=map[heng][zong-1];
e=map[heng][zong+1];
if(map[heng][zong]=='b')
map[heng][zong]='w';
else map[heng][zong]='b';
if(map[heng][zong-1]=='b')
map[heng][zong-1]='w';
else map[heng][zong-1]='b';
if(map[heng][zong+1]=='b')
map[heng][zong+1]='w';
else map[heng][zong+1]='b';
if(map[heng-1][zong]=='b')
map[heng-1][zong]='w';
else map[heng-1][zong]='b';
if(map[heng+1][zong]=='b')
map[heng+1][zong]='w';
else map[heng+1][zong]='b';
dfs(x+1,count+1);
map[heng][zong]=t;
map[heng-1][zong]=n;
map[heng+1][zong]=s;
map[heng][zong-1]=w;
map[heng][zong+1]=e;
}
dfs(x+1,count);
}
int main()
{
int i,j,sum;
for(i=0;i<4;i++)
for(j=0;j<4;j++)
cin>>map[i][j];
sum=0;
for(i=0;i<4;i++)
for(j=0;j<4;j++)
if(map[i][j]=='w')
sum=sum+1;
if(sum==16||sum==0)
cout<<0<<endl;
else {
mini=100000;
flag=0;
dfs(0,0);
if(flag==1)
cout<<mini<<endl;
else cout<<"Impossible"<<endl;
}
return 0;
}