OJ-Problems-Source/HDOJ/1813_autoAC.cpp

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#include <stdio.h>
#include <string.h>
#include <queue>
#include <algorithm>
using namespace std;
const int inf = 1000000000;
struct node
{
int x,y;
};
char str[4][10] = {"east","north","south","west"};
char map[9][9];
int to[4][2] = {0,1,-1,0,1,0,0,-1};
int L,n,dis[9][9],step,path[1000];
queue<node> Q;
int onedge(int i,int j)
{
return i==0 || j == 0 || i == n-1 || j == n-1;
}
int ismap(int i,int j)
{
return i>=0 && i<n && j>=0 && j<n;
}
void bfs()
{
int i;
node a,next;
while(!Q.empty())
{
a = Q.front();
Q.pop();
for(i = 0; i<4; i++)
{
next.x=a.x+to[i][0];
next.y=a.y+to[i][1];
if(!ismap(next.x,next.y)) continue;
if(!map[next.x][next.y]) continue;
if(dis[next.x][next.y]>dis[a.x][a.y]+1)
{
dis[next.x][next.y]=dis[a.x][a.y]+1;
Q.push(next);
}
}
}
}
void init()
{
int i,j,k;
node a;
while(!Q.empty()) Q.pop();
for(i = 0; i<n; i++)
{
for(j = 0; j<n; j++)
{
dis[i][j] = inf;
map[i][j] = map[i][j]=='1'?0:1;
if(!map[i][j]) continue;
if(onedge(i,j))
{
a.x = i;
a.y = j;
dis[i][j] = 0;
Q.push(a);
}
}
}
bfs();
}
int get_h(char mat[9][9])
{
int i,j,k,maxn = 0;
for(i = 0; i<n; i++)
{
for(j = 0; j<n; j++)
{
if(mat[i][j])
maxn = max(maxn,dis[i][j]);
}
}
return maxn;
}
int IDA(char mat[9][9],int cnt)
{
if(cnt+get_h(mat)>step) return 0;
if(cnt == step) return 1;
int i,x,y,tx,ty;
char tem[9][9];
for(i = 0; i<4; i++)
{
memset(tem,0,sizeof(tem));
for(x = 0; x<n; x++)
{
for(y = 0; y<n; y++)
{
if(onedge(x,y) || !mat[x][y]) continue;
tx = x+to[i][0];
ty = y+to[i][1];
if(!map[tx][ty]) tem[x][y] = 1;
else tem[tx][ty] = 1;
}
}
path[cnt] = i;
if(IDA(tem,cnt+1)) return 1;
}
return 0;
}
int main()
{
int i,j,k,flag = 0;
while(~scanf("%d",&n))
{
if(flag++)
printf("\n");
for(i = 0; i<n; i++)
scanf("%s",map[i]);
init();
step = 0;
while(1)
{
if(IDA(map,0))break;
step++;
}
for(i = 0; i<step; i++)
printf("%s\n",str[path[i]]);
}
return 0;
}