HDU 1010: Tempter of the Bone

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///@link http://acm.hdu.edu.cn/showproblem.php?pid=1010
///@author Sycamore
///@date Aug, 18

//fast DFS with pruning
#include<bits/stdc++.h>

using namespace std;
struct coord
{
   int x, y;
} s, d;
int n, m, t, cnt, dir[4][2] = {{1,  0},
                               {-1, 0},
                               {0,  1},
                               {0,  -1}};
char maze[7][7];

bool in_maze(int x, int y)
{
   return x >= 0 && x < n && y >= 0 && y < m;
}

bool dfs(coord cur, int dep)
{
   //cout<<cur.x<<‘ ‘<<cur.y<<‘ ‘<<dep<<endl; debug

   //base cases
   if (dep == t && cur.x == d.x && cur.y == d.y)return true;
   if (dep >= t)return false;

   for (int i = 0; i < 4; i++)
   {
      if (in_maze(cur.x + dir[i][0], cur.y + dir[i][1]))
         if (maze[cur.x + dir[i][0]][cur.y + dir[i][1]] != ‘X‘)
         {
            maze[cur.x][cur.y] = ‘X‘;//avoids revisits
            if (dfs(coord{cur.x + dir[i][0], cur.y + dir[i][1]}, dep + 1))
               return true;
            maze[cur.x][cur.y] = ‘.‘;//restores the path
         }

   }
   return false;
}

void solve()
{
   if (((abs(s.x - d.x) + abs(s.y - d.y)) & 1) != (t & 1) || cnt < t)
   {
      cout << "NO\n";
      return;
   }
   if (dfs(coord{s.x, s.y}, 0))cout << "YES\n";
   else cout << "NO\n";
}

int main()
{
   ios::sync_with_stdio(false);
   cin.tie(0);
   while (cin >> n >> m >> t && (n || m || t))
   {
      cnt = 1;
      for (int i = 0; i < n; i++)
         for (int j = 0; j < m; j++)
         {
            cin >> maze[i][j];
            if (maze[i][j] == ‘S‘)s = coord{i, j};
            else if (maze[i][j] == ‘D‘)d = coord{i, j};
            else if (maze[i][j] == ‘.‘)cnt++;
         }

      solve();
   }

   return 0;
}

HDU 1010: Tempter of the Bone

标签：ios   return   ack   auth   hdu   store   href   while   tor   

原文地址：http://www.cnblogs.com/zjnu/p/7389078.html