HDU1253--胜利大逃亡--简单BFS

Posted 2020-08-18 Pic

 

胜利大逃亡

Time Limit: 4000/2000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 21759    Accepted Submission(s): 8538

Problem Description

 

Ignatius被魔王抓走了,有一天魔王出差去了,这可是Ignatius逃亡的好机会.
魔王住在一个城堡里,城堡是一个A*B*C的立方体,可以被表示成A个B*C的矩阵,刚开始Ignatius被关在(0,0,0)的位置,离开城堡的门在(A-1,B-1,C-1)的位置,现在知道魔王将在T分钟后回到城堡,Ignatius每分钟能从一个坐标走到相邻的六个坐标中的其中一个.现在给你城堡的地图,请你计算出Ignatius能否在魔王回来前离开城堡(只要走到出口就算离开城堡,如果走到出口的时候魔王刚好回来也算逃亡成功),如果可以请输出需要多少分钟才能离开,如果不能则输出-1.

 

 

 

Input

 

输入数据的第一行是一个正整数K,表明测试数据的数量.每组测试数据的第一行是四个正整数A,B,C和T(1<=A,B,C<=50,1<=T<=1000),它们分别代表城堡的大小和魔王回来的时间.然后是A块输入数据(先是第0块,然后是第1块,第2块......),每块输入数据有B行,每行有C个正整数,代表迷宫的布局,其中0代表路,1代表墙.(如果对输入描述不清楚,可以参考Sample Input中的迷宫描述,它表示的就是上图中的迷宫)
特别注意:本题的测试数据非常大,请使用scanf输入,我不能保证使用cin能不超时.在本OJ上请使用Visual C++提交.

 

Output

 

对于每组测试数据,如果Ignatius能够在魔王回来前离开城堡,那么请输出他最少需要多少分钟,否则输出-1. 

 

Sample Input

 

1

3 3 4 20

0 1 1 1

0 0 1 1

0 1 1 1

1 1 1 1

1 0 0 1

0 1 1 1

0 0 0 0

0 1 1 0

0 1 1 0

 

Sample Output

 

11

 

/*-----------------------------------------------------------------------

转自http://www.cnblogs.com/yuyixingkong/p/3245297.html

代码是我的..

本题是搜索题，从囚徒出发，搜索到出口的最短路线的距离值（或者反向，由出口开始，搜索到囚徒的位置的距离值），容易想到的是宽度优先搜索，首先将囚徒的点放入先进先出的一个队列，并记录走过的时间（或距离），以后不断地

（1）将队列中先进的元素推出，还原为实际储存点后，

（2）六向搜索通路点，并将搜索到的通路点放进先进先出队列。

（3）重复（1），（2），直到搜索到目标点（出口）或队列为空为止，前者只要搜索得的值低于题目给出的T值，就输出此值，其余情况输出-1；

-------------------------------------------------------------------------

本题目有几个大坑：

1，门有可能是墙壁;（墙壁不可出，但是一开始人站的地方是墙居然又可以）

2,题目给出的某些CASE的T值小于囚徒到门口的空间最短距离（A+B+C-3）。不要忘记-1的情况

3，开始可以是墙，不影响，

掉进去会使用时增多，如果你的搜索效率再不高的，就很可能超时了。

----------------------------------------------------------------------------------*/

链接：http://acm.hdu.edu.cn/showproblem.php?pid=1253

这道题没什么特别难的地方，只是有几个bug要注意一下

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<map>
#include<iomanip>
#include<queue>
#define INF 0x7ffffff
#define MAXN 51
using namespace std;
const double eps=1e-10;
int m[MAXN][MAXN][MAXN];
int dir[6][3]={{1,0,0},{-1,0,0},{0,1,0},{0,-1,0},{0,0,1},{0,0,-1}};
struct node
{
    int a;
    int b;
    int c;
    int n;
};
int vis[MAXN][MAXN][MAXN];
int x,y,z;
int a,b,c;
int n;
int nn;
bool ok()
{
    if(x>=0&&x<a&&y>=0&&y<b&&z>=0&&z<c)
        return 1;
    else return 0;
}
int BFS()
{
    queue<struct node> route;
    struct node tem;
    struct node buf;
    buf.a=0;
    buf.b=0;
    buf.c=0;
    buf.n=0;
    vis[0][0][0]=1;
    route.push(buf);
    while(!route.empty()) {
        //cout<<11111<<endl;
        buf=route.front();
        route.pop();
        if(buf.a==a-1&&buf.b==b-1&&buf.c==c-1) {
            return buf.n;
        }
        if(buf.n>n){
            return -1;
        }
        //nn=buf.n+1;
        for(int i=0; i<6; i++){
            x=buf.a+dir[i][0];
            y=buf.b+dir[i][1];
            z=buf.c+dir[i][2];
            if(ok()&&m[x][y][z]==0&&vis[x][y][z]==0) {
                if(abs(x-a+1)+abs(y-a+1)+abs(z-c+1)+buf.n>n)//很棒的剪枝思路,见大坑2
                    continue;
                vis[x][y][z]=1;
                tem.a=x;
                tem.b=y;
                tem.c=z;
                tem.n=buf.n+1;
                route.push(tem);
            }
        }
    }
    return -1;
}
int main()
{
    #ifndef ONLINE_JUDGE
    freopen("data2.in", "r", stdin);
    #endif
    std::ios::sync_with_stdio(false);
    std::cin.tie(0);
    int t;
    int res=0;
    cin>>t;
    while(t--){
        a=b=c=x=y=z=0;
        nn=0;
        memset(vis,0,sizeof(vis));
        cin>>a>>b>>c>>n;
        for(int i=0;i<a;i++){
            for(int j=0;j<b;j++){
                for(int k=0;k<c;k++){
                    cin>>m[i][j][k];
                }
            }
        }
        cout<<BFS()<<endl;
    }
}


/*
5
3 3 4 20
0 1 1 1
0 0 1 1
0 1 1 1
1 1 1 1
1 0 0 1
0 1 1 1
0 0 0 0
0 1 1 0
0 1 1 0
3 3 4 20
1 1 1 1
0 0 1 1
0 1 1 1
1 1 1 1
1 0 0 1
0 1 1 1
0 0 0 0
0 1 1 0
0 1 1 0
3 3 4 20
0 1 1 1
0 0 1 1
0 1 1 1
1 1 1 1
1 0 0 1
0 1 1 1
0 0 0 0
0 1 1 0
0 1 1 1
3 3 4 10
0 1 1 1
0 0 1 1
0 1 1 1
1 1 1 1
1 0 0 1
0 1 1 1
0 0 0 0
0 1 1 0
0 1 1 0
3 3 4 21
0 1 1 1
0 0 1 1
0 1 1 1
1 1 1 1
1 0 0 1
0 1 1 1
0 0 1 0
0 1 1 0
0 1 1 0
*/

/*
11
11
-1
-1
-1
*/

还有一道一模一样的题目，在此也一并贴出

 

 

Asteroids!

 

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)

Total Submission(s): 114 Accepted Submission(s): 91

Problem Description You\'re in space. You want to get home. There are asteroids. You don\'t want to hit them.

Input Input to this problem will consist of a (non-empty) series of up to 100 data sets. Each data set will be formatted according to the following description, and there will be no blank lines separating data sets. A single data set has 5 components: Start line - A single line, "START N", where 1 <= N <= 10. Slice list - A series of N slices. Each slice is an N x N matrix representing a horizontal slice through the asteroid field. Each position in the matrix will be one of two values: \'O\' - (the letter "oh") Empty space \'X\' - (upper-case) Asteroid present Starting Position - A single line, "A B C", denoting the <A,B,C> coordinates of your craft\'s starting position. The coordinate values will be integers separated by individual spaces. Target Position - A single line, "D E F", denoting the <D,E,F> coordinates of your target\'s position. The coordinate values will be integers separated by individual spaces. End line - A single line, "END" The origin of the coordinate system is <0,0,0>. Therefore, each component of each coordinate vector will be an integer between 0 and N-1, inclusive. The first coordinate in a set indicates the column. Left column = 0. The second coordinate in a set indicates the row. Top row = 0. The third coordinate in a set indicates the slice. First slice = 0. Both the Starting Position and the Target Position will be in empty space.

Output For each data set, there will be exactly one output set, and there will be no blank lines separating output sets. A single output set consists of a single line. If a route exists, the line will be in the format "X Y", where X is the same as N from the corresponding input data set and Y is the least number of moves necessary to get your ship from the starting position to the target position. If there is no route from the starting position to the target position, the line will be "NO ROUTE" instead. A move can only be in one of the six basic directions: up, down, left, right, forward, back. Phrased more precisely, a move will either increment or decrement a single component of your current position vector by 1.

Sample Input START 1 O 0 0 0 0 0 0 END START 3 XXX XXX XXX OOO OOO OOO XXX XXX XXX 0 0 1 2 2 1 END START 5 OOOOO OOOOO OOOOO OOOOO OOOOO OOOOO OOOOO OOOOO OOOOO OOOOO XXXXX XXXXX XXXXX XXXXX XXXXX OOOOO OOOOO OOOOO OOOOO OOOOO OOOOO OOOOO OOOOO OOOOO OOOOO 0 0 0 4 4 4 END

Sample Output 1 0 3 4 NO ROUTE

Source South Central USA 2001

Recommend zf

下面是AC代码

#include <string.h>
#include <stdio.h>
#include <queue>
using namespace std;

char map[20][20][20];
int vis[20][20][20];
int n;
int sx,sy,sz;
int ex,ey,ez;
int tx[] = {1,-1,0,0,0,0};
int ty[] = {0,0,1,-1,0,0};
int tz[] = {0,0,0,0,1,-1};

struct node
{
    int x,y,z,step;
};

int check(int x,int y,int z)
{
    if(x<0 || y<0 || z<0 || x>=n || y>=n || z>=n || vis[x][y][z] )
    return 0;
    return 1;
}

int bfs(int x,int y,int z)
{
    int i;
    queue<node> Q;
    node a,next;
    a.x = x;
    a.y = y;
    a.z = z;
    a.step = 0;
    vis[x][y][z] = 1;
    Q.push(a);
    while(!Q.empty())
    {
        a = Q.front();
        Q.pop();
        if(a.x == ex && a.y == ey && a.z == ez)
        return a.step;
        for(i = 0;i<6;i++)
        {
            next = a;
            next.x+=tx[i];
            next.y+=ty[i];
            next.z+=tz[i];
            if(check(next.x,next.y,next.z))
            {
                next.step++;
                vis[next.x][next.y][next.z] = 1;
                Q.push(next);
            }
        }
    }
    return -1;
}

int main()
{
    char s[10];
    int i,j,k;
    while(~scanf("%s%d",s,&n))
    {
        for(i = 0;i<n;i++)
        for(j = 0;j<n;j++)
        scanf("%s",map[i][j]);
        scanf("%d%d%d%d%d%d",&sx,&sy,&sz,&ex,&ey,&ez);
        scanf("%s",s);
        int ans = bfs(sx,sy,sz);
        if(ans>=0)
        printf("%d %d\\n",n,ans);
        else
        printf("NO ROUTE\\n");
    }

    return 0;
}