【HDOJ】1026 Ignatius and the Princess I

这道题搞了很久啊。搜索非常好的一道题。昨天想了2小时，以为是深搜，但后来发现深搜怎么也没法输出正确路径。今天拿宽搜试了一下，问题就是普通的队列宽搜没法得到当前时间最小值。看了一下讨论区，发现优先级队列。好久不用了，都忘记了。各种忘记，优先级队列排序都忘掉了。搞了好半天。最后还需要注意的是格式化输出，采用栈格式输出。需要保存每个节点的移动方向。并且注意若终点是怪兽，还是需要"Fight"。这道题目感觉不是一道水题，还挺不错。

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

 #define MAXNUM 105
 #define isDigit(ch) ch>='0' && ch<='9'

 typedef struct node_st{
     int x, y, time;
     node_st() {

     }
     node_st(int a, int b, int t) {
         x = a; y = b; time = t;
     }
     friend bool operator < (node_st p, node_st q) {
         return p.time > q.time;
     }
 } node_st;

 priority_queue<node_st> que;

 typedef struct subnode {
     int x, y;
     subnode() {

     }
     subnode (int a, int b) {
         x = a; y = b;
     }
 } subnode;

 stack<subnode> path;
 char map[MAXNUM][MAXNUM];
 bool visit[MAXNUM][MAXNUM];
 int pos[MAXNUM][MAXNUM];
 int direct[][]={{,-}, {-,}, {,}, {,}};
 int n, m;

 void output();

 bool check(int x, int y) {
     if (x>= && x<n && y>= && y<m) {
         if (visit[x][y]==false && map[x][y]!='X')
             return true;
         else
             return false;
     } else
         return false;
 }

 void bfs() {
     node_st cur, next;
     int newx, newy, newt;

     que.push(node_st(,,));
     visit[][] = true;
     while ( !que.empty() ) {
         cur = que.top();
         que.pop();
         // printf("cur node: x=%d,y=%d,cur.time=%d\n",cur.x, cur.y, cur.time);
         if (cur.x==n- && cur.y==m-) {
             printf("It takes %d seconds to reach the target position, let me show you the way.\n", cur.time);
             output();
             printf("FINISH\n");
             return ;
         }
         for (int i=; i<; ++i) {
             newx = cur.x + direct[i][];
             newy = cur.y + direct[i][];
             newt = cur.time + ;
             if ( check(newx, newy) ) {
                 next = node_st(newx, newy, newt);
                 if ( isDigit(map[newx][newy]) )
                     next.time += map[newx][newy] - '';
                 // printf("after check, ch=%c, time=%d\n", map[newx][newy], next.time);
                 pos[newx][newy] = i;
                 visit[newx][newy] = true;
                 que.push(next);
             }
         }
     }
     printf("God please help our poor hero.\n");
     printf("FINISH\n");
 }

 int main() {
     int i;

     while (scanf("%d %d", &n, &m) != EOF) {
         getchar();
         for (i=; i<n; ++i) {
             gets(map[i]);
         }
         memset(visit, false, sizeof(visit));
         memset(pos, , sizeof(pos));
         while (!que.empty())
             que.pop();
         while (!path.empty())
             path.pop();
         bfs();
     }

     return ;
 }

 void output() {
     subnode cur, next;
     int x, y, i, time = ;

     x = n-; y =m-;
     while (x||y) {
         path.push(subnode(x, y));
         i = pos[x][y];
         x -= direct[i][];
         y -= direct[i][];
     }
     // Don;t forget to push (0, 0)
     path.push(subnode(, ));

     cur = path.top();
     path.pop();

     while (!path.empty()) {
         next = path.top();

         x = cur.x;
         y = cur.y;
         if (map[x][y] != '.') {
             i = map[x][y] - '';
             while (i--) {
                 printf("%ds:FIGHT AT (%d,%d)\n", ++time, x, y);
             }
         }
         time++;
         printf("%ds:(%d,%d)->(%d,%d)\n", time, cur.x, cur.y, next.x, next.y);

         cur = path.top();
         path.pop();
     }
     // if final-point has a monster, then ight
     x = next.x;
     y = next.y;
     if (map[x][y] != '.') {
         i = map[x][y] - '';
         while (i--) {
             printf("%ds:FIGHT AT (%d,%d)\n", ++time, x, y);
         }
     }
 }