【HDOJ】2782 The Worm Turns

DFS。

 /* 2782 */
 #include <iostream>
 #include <queue>
 #include <cstdio>
 #include <cstring>
 #include <cstdlib>
 using namespace std;

 #define MAXN 650

 int n, m;
 bool visit[MAXN][MAXN];
 int ansd, ansx, ansy, ansb;
 int dir[][] = {
      // E, N, S, W.
      ,, -,, ,, ,-
 };
 int link[][] = {
     ,, ,, ,, ,
 };
 char op[] = "ENSW";

 inline bool check(int x, int y) {
     return x< || x>=n || y< || y>=m;
 }

 int dfs(int x, int y, int d) {
     int i, j, k, tmp;
     int xx, yy;
     int ret = ;

     if (d == -) {
         for (i=; i<; ++i) {
             xx = x + dir[i][];
             yy = y + dir[i][];
             if (check(xx, yy) || visit[xx][yy])
                 continue;
             k = ;
             while (!check(xx, yy) && !visit[xx][yy]) {
                 ++k;
                 visit[xx][yy] = true;
                 xx += dir[i][];
                 yy += dir[i][];
             }
             xx -= dir[i][];
             yy -= dir[i][];
             tmp = k + dfs(xx, yy, i);
             if (tmp > ansb) {
                 ansb = tmp;
                 ansx = x;
                 ansy = y;
                 ansd = i;
             }
             while (k--) {
                 visit[xx][yy] = false;
                 xx -= dir[i][];
                 yy -= dir[i][];
             }
         }
     } else {
         for (j=; j<; ++j) {
             i = link[d][j];
             xx = x + dir[i][];
             yy = y + dir[i][];
             if (check(xx, yy) || visit[xx][yy])
                 continue;
             k = ;
             while (!check(xx, yy) && !visit[xx][yy]) {
                 ++k;
                 visit[xx][yy] = true;
                 xx += dir[i][];
                 yy += dir[i][];
             }
             xx -= dir[i][];
             yy -= dir[i][];
             tmp = k + dfs(xx, yy, i);
             if (tmp > ret)
                 ret = tmp;
             while (k--) {
                 visit[xx][yy] = false;
                 xx -= dir[i][];
                 yy -= dir[i][];
             }
         }
     }
     return ret;
 }

 int main() {
     int t = ;
     int i, j, k;

     #ifndef ONLINE_JUDGE
         freopen("data.in", "r", stdin);
     #endif

     while (scanf("%d %d",&n,&m)!=EOF && (n||m)) {
         memset(visit, false, sizeof(visit));
         scanf("%d", &k);
         while (k--) {
             scanf("%d %d", &i, &j);
             visit[i][j] = true;
         }
         ansb = -;
         for (i=; i<n; ++i) {
             for (j=; j<m; ++j) {
                 if (!visit[i][j]) {
                     visit[i][j] = true;
                     dfs(i, j, -);
                     visit[i][j] = false;
                 }
             }
         }
         printf("Case %d: %d %d %d %c\n", ++t, ansb+, ansx, ansy, op[ansd]);
     }

     return ;
 }