hdu

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

求起点到终点的最少花费，输出路径的时候麻烦一点，借鉴了别人的思路，用dfs 递归打印出路径。

用额外一个二维数组标记当前点的前驱，因为点是一个坐标，那么可以用 s=x*m+y 映射成一个点就可以了。

这样知道这个数值在求出坐标的话，x=s/m,y=s%m。

#include <iostream>
#include <cstdio>
#include <cmath>
#include <vector>
#include <cstring>
#include <string>
#include <algorithm>
#include <string>
#include <set>
#include <functional>
#include <numeric>
#include <sstream>
#include <stack>
#include <map>
#include <queue>
#pragma comment(linker, "/STACK:102400000,102400000")
#define CL(arr, val)    memset(arr, val, sizeof(arr))

#define ll long long
#define inf 0x7f7f7f7f
#define lc l,m,rt<<1
#define rc m + 1,r,rt<<1|1
#define pi acos(-1.0)

#define L(x)    (x) << 1
#define R(x)    (x) << 1 | 1
#define MID(l, r)   (l + r) >> 1
#define Min(x, y)   (x) < (y) ? (x) : (y)
#define Max(x, y)   (x) < (y) ? (y) : (x)
#define E(x)        (1 << (x))
#define iabs(x)     (x) < 0 ? -(x) : (x)
#define OUT(x)  printf("%I64d
", x)
#define lowbit(x)   (x)&(-x)
#define Read()  freopen("a.txt", "r", stdin)
#define Write() freopen("b.txt", "w", stdout);
#define maxn 1000000000
#define N 2510
#define mod 1000000000
using namespace std;

char field[110][110];
int used[110][110];
int n,m,time;
int dir[4][2]={{-1,0},{1,0},{0,-1},{0,1}};
struct point
{
    int x,y,step;
    bool operator < (const point a) const
    {
        return step>a.step;
    }
};
int bfs()
{
    point s;
    s.x=0,s.y=0,s.step=0;
    priority_queue<point>que;
    que.push(s);
    while(!que.empty())
    {
        point e=que.top();
        que.pop();
        if(e.x==n-1&&e.y==m-1) return e.step;
        for(int i=0;i<4;i++)
        {
            s=e;
            s.x=e.x+dir[i][0];
            s.y=e.y+dir[i][1];
            if(s.x>=0&&s.x<n&&s.y>=0&&s.y<m&&field[s.x][s.y]!='X'&&used[s.x][s.y]==-1)
            {
                used[s.x][s.y]=e.x*m+e.y;
                s.step+=1;
                char c=field[s.x][s.y];
                if(c>='0'&&c<='9') s.step+=c-'0';
                //printf("%d %d %d
",e.x,e.y,e.step);
                que.push(s);
            }
        }
    }
    return 0;
}

void get_path(int x,int y)
{
    if(x==0&&y==0) return;
   // printf("%d
",used[x][y]);
    int a=used[x][y]/m,b=used[x][y]%m;
    get_path(a,b);
    printf("%ds:(%d,%d)->(%d,%d)
",time++,a,b,x,y);
    if(field[x][y]>='0'&&field[x][y]<='9')
    {
        while(field[x][y]>'0')
        {
            printf("%ds:FIGHT AT (%d,%d)
",time++,x,y);
            field[x][y]--;
        }
    }
}
int main()
{
   // freopen("a.txt","r",stdin);
    while(~scanf("%d%d",&n,&m))
    {
        getchar();
        for(int i=0;i<n;i++)
        {
            scanf("%s",field[i]);
        }
        memset(used,-1,sizeof(used));
        int flag=bfs();
        if(flag)
        {
            printf("It takes %d seconds to reach the target position, let me show you the way.
",flag);
            time=1;
            get_path(n-1,m-1);
        }
        else printf("God please help our poor hero.
");
        printf("FINISH
");
    }
    return 0;
}