【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[4][2]={{0,-1}, {-1,0}, {0,1}, {1,0}};
int n, m;

void output();

bool check(int x, int y) {
    if (x>=0 && x<n && y>=0 && 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(0,0,0));
    visit[0][0] = 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-1 && cur.y==m-1) {
            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=0; i<4; ++i) {
            newx = cur.x + direct[i][0];
            newy = cur.y + direct[i][1];
            newt = cur.time + 1;
            if ( check(newx, newy) ) {
                next = node_st(newx, newy, newt);
                if ( isDigit(map[newx][newy]) )
                    next.time += map[newx][newy] - '0';
                // 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=0; i<n; ++i) {
            gets(map[i]);
        }
        memset(visit, false, sizeof(visit));
        memset(pos, 0, sizeof(pos));
        while (!que.empty())
            que.pop();
        while (!path.empty())
            path.pop();
        bfs();
    }

    return 0;
}

void output() {
    subnode cur, next;
    int x, y, i, time = 0;

    x = n-1; y =m-1;
    while (x||y) {
        path.push(subnode(x, y));
        i = pos[x][y];
        x -= direct[i][0];
        y -= direct[i][1];
    }
    // Don;t forget to push (0, 0)
    path.push(subnode(0, 0));

    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] - '0';
            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] - '0';
        while (i--) {
            printf("%ds:FIGHT AT (%d,%d)\n", ++time, x, y);
        }
    }
}