76 lines
1.6 KiB
C++
76 lines
1.6 KiB
C++
#include<stdio.h>
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#include<string.h>
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#include<queue>
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using namespace std;
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#define inf 999999999
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struct node
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{
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int x,y,time;
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friend bool operator<(node a,node b)
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{
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return a.time>b.time;
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}
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};
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char map[1010][1010];
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int visit[1010][1010];
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int dir[4][2]={1,0,0,1,-1,0,0,-1};
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int n,m;
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int judge(int x,int y)
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{
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if(x>=1&&x<=n&&y>=1&&y<=m)
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return 1;
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return 0;
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}
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int bfs(int sx,int sy,int dx,int dy)
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{
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priority_queue<node>q;
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node in,out;
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int i;
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visit[sx][sy]=0;
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in.x=sx;
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in.y=sy;
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in.time=0;
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q.push(in);
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while(!q.empty())
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{
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in=q.top();
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q.pop();
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if(in.x==dx&&in.y==dy)
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return in.time;
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for(i=0;i<4;i++)
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{
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out.x=in.x+dir[i][0];
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out.y=in.y+dir[i][1];
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if(judge(out.x,out.y))
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{
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if(map[out.x][out.y]=='X')
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out.time=in.time;
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else
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out.time=in.time+1;
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if(visit[out.x][out.y]>out.time)
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{
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visit[out.x][out.y]=out.time;
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q.push(out);
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}
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}
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}
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}
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return 1;
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}
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int main()
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{
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int x0,y0,x1,y1,i,j,ans;
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while(scanf("%d%d",&n,&m),n+m)
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{
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for(i=1;i<=n;i++)
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scanf("%s",map[i]+1);
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for(i=1;i<=n;i++)
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for(j=1;j<=m;j++)
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visit[i][j]=inf;
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scanf("%d%d%d%d",&x0,&y0,&x1,&y1);
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ans=bfs(x0,y0,x1,y1);
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printf("%d\n",ans);
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}
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return 0;
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}
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