蓝桥杯——九宫重排(八数码问题)

#include<iostream>
#include<cstdio>
#include<cstring>
#include<vector>
#include<algorithm>
#include<cmath>
#include<queue>
#include<map>
#include<stack>
#include<set>
using namespace std;
typedef long long ll;
const int maxn=20010;
const int inf=0xfffffff;

char maze[5][5];
char ans[5][5];
char a[10],b[10],ai=1,bi=1;

bool isjie(){
int i,j;
int ans1=0;
for(i=2;i<=9;++i){
if(a[i]=='.') continue;
int sum=0;
for(j=1;j<i;++j){
if(a[j]=='.') continue;
if(a[j]>a[i]){
sum++;
}
}
ans1+=sum;
}
int ans2=0;
for(i=2;i<=9;++i){
if(b[i]=='.') continue;
int sum=0;
for(j=1;j<i;++j){
if(b[j]=='.') continue;
if(b[j]>b[i]){
sum++;
}
}
ans2+=sum;
}
ans1=ans1&1;
ans2=ans2&1;
if(ans1^ans2){
return false;
}
return true;

}

int geth(){
int i,j,sum=0;
for(i=1;i<=3;++i){
for(j=1;j<=3;++j){
char c=ans[i][j];
if(c=='.') continue;
for(int k=1;k<=3;++k){
for(int l=1;l<=3;++l){
if(maze[k][l]==c){
sum+=fabs(i-k)+fabs(j-l);
break;
}
}
}
}
}
return sum;
}

bool flag;
int dr[4][2]={-1,0,0,-1,0,1,1,0};
int q;

void dfs(int x,int y,int last,int now,int step){
int h=geth();
if(now<=step){
if(h==0){
flag=true;
q=now;
return;
}else if(now==step) return;
}
int nx,ny;
for(int i=0;i<4;++i){
if(i+last==3&&now>0) continue;
nx=x+dr[i][0];
ny=y+dr[i][1];
if(nx>=1&&nx<=3&&ny>=1&&ny<=3){
swap(maze[x][y],maze[nx][ny]);
if(geth()+now<=step && !flag){
dfs(nx,ny,i,now+1,step);
if(flag) return;
}
swap(maze[x][y],maze[nx][ny]);
}
}

}

int main(){
int i,j;
int st,se;
for(i=1;i<=3;++i)
for(j=1;j<=3;++j){
scanf("%c",&maze[i][j]);
a[ai++]=maze[i][j];
if(maze[i][j]=='.'){
st=i,se=j;
}
}
getchar();
for(i=1;i<=3;++i)
for(j=1;j<=3;++j){
scanf("%c",&ans[i][j]);
b[bi++]=ans[i][j];
}
if(!isjie()){
puts("-1");
return 0;
}
int dep=1;
while(1){
flag=false;
dfs(st,se,0,0,dep);
if(flag){
printf("%d\n",q);
break;
}
++dep;
}
return 0;
}