hdu 5067 Harry And Dig Machine（BestCoder Round #14)

浏览数：29 / 时间：2015年06月20日

Harry And Dig Machine

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 332 Accepted Submission(s): 104

Problem Description

As we all know, Harry Porter learns magic at Hogwarts School. However, learning magical knowledge alone is insufficient to become a great magician. Sometimes, Harry also has to gain knowledge from other certain subjects, such as language, mathematics, English, and even algorithm.
Dumbledore, the headmaster of Hogwarts, is planning to construct a new teaching building in his school. The area he selects can be considered as an n*m grid, some (but no more than ten) cells of which might contain stones. We should remove the stones there in order to save place for the teaching building. However, the stones might be useful, so we just move them to the top-left cell. Taking it into account that Harry learned how to operate dig machine in Lanxiang School several years ago, Dumbledore decides to let him do this job and wants it done as quickly as possible. Harry needs one unit time to move his dig machine from one cell to the adjacent one. Yet skilled as he is, it takes no time for him to move stones into or out of the dig machine, which is big enough to carry infinite stones. Given Harry and his dig machine at the top-left cell in the beginning, if he wants to optimize his work, what is the minimal time Harry needs to finish it?

Input

They are sever test cases, you should process to the end of file.
For each test case, there are two integers n and m.

(1≤n,m≤50).
The next n line, each line contains m integer. The j-th number of

ith line a[i][j] means there are a[i][j] stones on the

jth cell of the

ith line.(

0≤a[i][j]≤100 , and no more than 10 of a[i][j] will be positive integer).

Output

For each test case, just output one line that contains an integer indicate the minimal time that Harry can finish his job.

Sample Input

Sample Output

4
4

Source

BestCoder Round #14

知道是状压DP题，怎么都想不到思路，在最后写了个dfs交了一发，但写程序想到的剪枝忘写了，加上刚好结束，最后终测时TLE，加了剪枝就过了。由于就10个点，dfs复杂度为10！，再加个剪枝还是可以过的，状压DP的还没会，先占个坑，会了再补上。

我的dfs代码：

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
int a[100][100];
struct node
{
    int x;
    int y;
}p[100];
int bbs(int x)
{
    if(x<0)
    return -x;
    return x;
}
bool visit[100];
int t;
int ans;
void dfs(int v,int temp,node u)
{
   if(temp>ans)//剪枝
   return;
    if(v==0)//递归出口
    {
        temp=temp+u.x+u.y;
        if(temp<ans)
        ans=temp;
        return;
    }
    int yu;
    for(int i=0;i<t;i++)
    {
        if(visit[i]==false)
        {
           yu=temp+bbs(p[i].x-u.x)+bbs(p[i].y-u.y);
            visit[i]=true;
            dfs(v-1,yu,p[i]);
            visit[i]=false;
        }
    }
    return;
}
int main()
{
    int n,m;
    while(~scanf("%d%d",&n,&m))
    {
        int w;
        t=0;
        for(int i=0;i<n;i++)
        for(int j=0;j<m;j++)
        {
            scanf("%d",&w);
            if(j==0&&i==0)
            continue;
            if(w)
            {
                p[t].x=i;
                p[t++].y=j;
            }
        }
        memset(visit,false,sizeof(visit));
        ans=99999999;
        int temp=0;
        node u;
        u.x=0;
        u.y=0;
        dfs(t,temp,u);
        printf("%d\n",ans);
    }
    return 0;
}

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hdu 5067 Harry And Dig Machine（BestCoder Round #14)

标签： algorithmalgorithm