HDU 1241 Oil Deposits(dfs)

#include<cstdio>

#include<cmath>

#include<cstring>

#include<iostream>

#include<algorithm>

using namespace std;

char mat[10][10];

int vis[10][10];

int ok,dx,dy;

int m,n,d;

int op[4][2]={0,1,1,0,0,-1,-1,0};

bool jiezhi(int x,int y,int rt)

{

  int now=abs(dx-x)+abs(dy-y);

  if(d-rt<now) return false;

  if((d-rt-now)%2!=0) return true;

  return true;

}

bool okn(int x,int y,int rt)

{

  if(x<0||x>=n||y<0||y>=m||rt>d||vis[x][y]==1||mat[x][y]=='X') return false;

  if(rt<d&&mat[x][y]=='D') return false;

  if(rt==d)

  {

    if(mat[x][y]=='D') ok=1;

    return false;

  }

  return true;

}

void dfs(int x,int y,int rt)

{

  if(jiezhi(x,y,rt)!=1||ok) return;

  int nx,ny;

  for(int i=0;i<4;i++)

  {

    nx=x+op[i][0];

    ny=y+op[i][1];

    if(okn(nx,ny,rt+1))

    {

      vis[nx][ny]=1;

      dfs(nx,ny,rt+1);

      vis[nx][ny]=0;

    }

  }

}

int main()

{

  int i,j,k;

  int sx,sy;

    while(scanf("%d%d%d",&n,&m,&d)!=EOF)

    {

        if(n==0||m==0||d==0) break;

        ok=0;

        for(i=0; i<n; i++)

        {

            scanf("%s",mat[i]);

        }

        memset(vis,0,sizeof(vis));



        for(i=0; i<n; i++)

            for(j=0; j<m; j++)

                {

                  if(mat[i][j]=='S')

                  {

                    sx=i;

                    sy=j;

                  }

                  else if(mat[i][j]=='D')

                  {

                    dx=i;dy=j;

                  }

                }

        if(jiezhi(sx,sy,0))

        {

          vis[sx][sy]=1;

          dfs(sx,sy,0);

        }

        if(ok) printf("YES\n");

        else printf("NO\n");

    }

  return 0;

}

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