【HDOJ】1983 Kaitou Kid - The Phantom Thief (2)

不仅仅是DFS，还需要考虑可以走到终点。同时，需要进行预处理。至多封闭点数为起点和终点的非墙壁点的最小值。

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

 typedef struct node_st {
     int x, y, t, flg;
     node_st() {}
     node_st(int xx, int yy, int tt, int fflg) {
         x=xx; y=yy; t=tt; flg=fflg;
     }
 } node_st;

 char map[][];
 char visit[][][];
 int direct[][] = {{-,},{,},{,-},{,}};
 int n, m, time, fmin;
 int begx, begy, endx, endy;

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

 bool bfs() {
     queue<node_st> que;
     int x, y, t, flg;
     int i;
     node_st node;

     memset(visit, , sizeof(visit));
     que.push(node_st(begx, begy, , ));
     visit[begx][begy][] = ;

     while ( !que.empty() ) {
         node = que.front();
         que.pop();
         t = node.t;
         if (t == time)
             break;
         for (i=; i<; ++i) {
             x = node.x + direct[i][];
             y = node.y + direct[i][];
             flg = node.flg;
             if ( !check(x, y) )
                 continue;
             if (map[x][y] != '#') {
                 if (map[x][y] == 'E' && flg==)
                     return true;
                 if (map[x][y] == 'J')
                     flg = ;
                 if (t<time && !visit[x][y][flg]) {
                     visit[x][y][flg] = ;
                     que.push(node_st(x, y, t+, flg));
                 }
             }
         }
     }

     return false;
 }

 void printmap() {
     for (int i=; i<n; ++i)
         printf("\t%s\n", map[i]);
 }

 int dfs(int t, int cur) {
     int flg = ;
     char ch;

     if (t >= fmin)
         return ;

     for (int i=; i<n; ++i) {
         for (int j=; j<m; ++j) {
             if (map[i][j]=='.' || map[i][j] == 'J') {
                 ch = map[i][j];
                 map[i][j] = '#';
                 if (cur == t) {
                     //printmap();
                     if ( !bfs() ) {
                         fmin = (t<fmin) ? t:fmin;
                         return ;
                     }
                 }
                 if (cur < t)
                     flg = dfs(t, cur+);
                 map[i][j] = ch;
             }
             if (flg)
                 return ;
         }
     }

     return ;
 }

 int pre() {
     int i, x, y, tmp1, tmp2;

     tmp1 = ;
     for (i=; i<; ++i) {
         x = begx + direct[i][];
         y = begy + direct[i][];
         if ( check(x, y) && (map[x][y]=='.'||map[x][y]=='J'))
             tmp1++;
     }

     tmp2 = ;
     for (i=; i<; ++i) {
         x = endx + direct[i][];
         y = endy + direct[i][];
         if ( check(x, y) && (map[x][y]=='.'||map[x][y]=='J'))
             tmp2++;
     }

     return tmp1<tmp2 ? tmp1 : tmp2;
 }

 int main() {
     int case_n;
     int i, j;

     scanf("%d", &case_n);

     while (case_n--) {
         scanf("%d %d %d%*c", &n, &m, &time);
         for (i=; i<n; ++i) {
             scanf("%s", map[i]);
             for (j=; j<m; ++j) {
                 if (map[i][j] == 'S') {
                     begx = i;
                     begy = j;
                 }
                 if (map[i][j] == 'E') {
                     endx = i;
                     endy = j;
                 }
             }
         }
         if ( !bfs() ) {
             printf("0\n");
             continue;
         }
         fmin = pre();
         //printf("pre:%d\n", fmin);
         dfs(,);
         //printf("1:%d\n", fmin);
         dfs(,);
         //printf("2:%d\n", fmin);
         dfs(,);
         printf("%d\n", fmin);
     }

     return ;
 }