HDU 1175 continuous view (DFS + pruning)

Some details are not handled well. Wa has been done many times.

Pruning is not strong, and it runs for more than 6000 ms.

View code

 1 /* 2 Author:Zhaofa Fang 3 Lang:C++ 4 */ 5 #include <cstdio> 6 #include <cstdlib> 7 #include <sstream> 8 #include <iostream> 9 10 #include <cstring>11 #include <algorithm>12 #include <string>13 #include <utility>14 #include <vector>15 #include <queue>16 #include <stack>17 #include <map>18 #include <set>19 20 using namespace std;21 22 typedef long long ll;23 #define DEBUG(x) cout<< #x << ':' << x << endl24 #define PII pair<int,int>25 #define PB push_back26 #define MP make_pair27 #define FI first28 #define SE second29 #define lowbit(x) (x&(-x))30 #define INF (1<<30)31 32 const double eps = 1e-6;33 34 int maz[1005][1005];35 int dx[]={1,0,0,-1};36 int dy[]={0,1,-1,0};37 bool OK;38 int n,m;39 int x1,y1,x2,y2;40 bool check(int x,int y)41 {42     if(x<1 || x>n || y<1 || y>m)return false;43     return true;44 }45 void dfs(int x,int y,int turn,int dire)46 {47     if(turn > 2 || !check(x,y))return;48     if(OK)return ;49     if(x == x2 && y == y2)50     {51         OK = 1;52         return;53     }54     for(int i=0;i<4;i++)55     {56         if(dire + i == 3)continue;57         int xx = x + dx[i];58         int yy = y + dy[i];59         if((xx != x2 || yy != y2) && maz[xx][yy] != 0)continue;60         if(dire != i && dire != -1)dfs(xx,yy,turn + 1,i);61         else dfs(xx,yy,turn,i);62     }63 }64 65 int main()66 {67     #ifndef ONLINE_JUDGE68     freopen("in","r",stdin);69     #endif70     while(~scanf("%d%d",&n,&m),n,m)71     {72         for(int i=1;i<=n;i++)73         {74             for(int j=1;j<=m;j++)75                 scanf("%d",&maz[i][j]);76         }77         int q;78         scanf("%d",&q);79         while(q--)80         {81             scanf("%d%d%d%d",&x1,&y1,&x2,&y2);82             if(maz[x1][y1] != maz[x2][y2]83             || maz[x1][y1] == 0 || maz[x2][y2] == 0)84             {85                 puts("NO");86                 continue;87             }88             OK=0;89             dfs(x1,y1,0,-1);90             if(OK)puts("YES");91             else puts("NO");92         }93     }94     return 0;95 }