HDU 1026 Ignatius and the Princess I

题目 http://acm.hdu.edu.cn/showproblem.php?pid=1026

BFS+优先队列，需要记录路径。

#include <iostream>
#include <stdio.h>
#include <queue>
using namespace std;
const int maxn=100;
const int inf=0x7fffffff;

struct map
{
    int  f, x, y, prex, prey, time;
    char c;
    bool operator <(const struct map &m1) const 
    {
        return m1.time<time;
    }
}mp[maxn+10][maxn+10];

int dx[4]={0, 1, 0, -1};
int dy[4]={-1, 0, 1, 0};
int m, n;
char cc[maxn+10];

int BFS()
{
    priority_queue<map> q;
    mp[0][0].time=0, mp[0][0].f=1;
    q.push(mp[0][0]);
    while (!q.empty())
    {
        struct map cur_m=q.top();
        q.pop();
        if (cur_m.x==n-1&&cur_m.y==m-1) return 1;
        for (int i=0; i<4; i++)
        {
            int newx=dx[i]+cur_m.x;
            int newy=dy[i]+cur_m.y;
            if (newx<0||newx>n-1||newy<0||newy>m-1||mp[newx][newy].f==1) continue;
            if (mp[newx][newy].c=='.')
            {
                mp[newx][newy].f=1, mp[newx][newy].time=mp[cur_m.x][cur_m.y].time+1;
                mp[newx][newy].x=newx, mp[newx][newy].y=newy;
                mp[newx][newy].prex=cur_m.x, mp[newx][newy].prey=cur_m.y;    
            }
            else if (isdigit(mp[newx][newy].c))
            {
                mp[newx][newy].f=1, mp[newx][newy].time=mp[cur_m.x][cur_m.y].time+(mp[newx][newy].c-'0')+1;
                mp[newx][newy].x=newx, mp[newx][newy].y=newy;
                mp[newx][newy].prex=cur_m.x, mp[newx][newy].prey=cur_m.y;
            }
            q.push(mp[newx][newy]);
        }
    }
    return 0;
}

void printTrace(int x, int y)
{
    if (x==0&&y==0) return;
    int prex=mp[x][y].prex, prey=mp[x][y].prey;
    printTrace(prex, prey);
    int len1=mp[prex][prey].time, len2=mp[x][y].time;
    printf("%ds:(%d,%d)->(%d,%d)\n", len1+1, prex, prey, x, y);
    for (int i=len1+2; i<=len2; i++) printf("%ds:FIGHT AT (%d,%d)\n", i, x, y);
}
int main()
{
    //freopen("in.txt", "r", stdin);
    while (scanf("%d %d", &n, &m)==2)
    {
        for (int i=0; i<n; i++)
        {    
            scanf("%s", cc);
            for (int j=0; j<m; j++)
            {
                mp[i][j].c=cc[j];
                if (mp[i][j].c=='X') mp[i][j].f=1;
                else mp[i][j].f=0;
                mp[i][j].time=inf, mp[i][j].x=i, mp[i][j].y=j;
            }
        }
        
        if (BFS())
        {
             printf("It takes %d seconds to reach the target position, let me show you the way.\n", mp[n-1][m-1].time);
             printTrace(n-1, m-1);
        }
        else printf("God please help our poor hero.\n");
        printf("FINISH\n");
    }
    return 0;
}