POJ 1011

Sticks
Time Limit: 1000MS Memory Limit: 10000K
Total Submissions: 135722 Accepted: 31924
Description

George took sticks of the same length and cut them randomly until all parts became at most 50 units long. Now he wants to return sticks to the original state, but he forgot how many sticks he had originally and how long they were originally. Please help him and design a program which computes the smallest possible original length of those sticks. All lengths expressed in units are integers greater than zero.
Input

The input contains blocks of 2 lines. The first line contains the number of sticks parts after cutting, there are at most 64 sticks. The second line contains the lengths of those parts separated by the space. The last line of the file contains zero.
Output

The output should contains the smallest possible length of original sticks, one per line.
Sample Input

9
5 2 1 5 2 1 5 2 1
4
1 2 3 4
0
Sample Output

6
5

一道经典的深搜题目。题目大意应该都懂。直接说思路：

1 木棒原长一定是>=给你的最大的棒子的长度，小于所以sticks之和！

2 不要搜索每个长度，只搜索 是总长度因数的长度就好！

3 搜索的时候要注意 当 剩余长度为0时需要把棒子补齐

4 相同长度的棒子只要搜索一次就好！

5 如果你当前的sticks 长度和剩余长度相同或者为0 就不要搜了。直接break;

6 vis数组！注意标记！

#include <string.h>#include <stdio.h>#include <iostream>#include <algorithm>#define maxs 166using namespace std;bool vis[maxs];int  sticks[maxs];int sum;int n;bool cmp(int a,int b){    return a>b;}int dfs(int n_len,int remain_len,int num_stick){    if(remain_len==0&&num_stick==0)        return n_len;    if(remain_len==0)        remain_len=n_len;    for(int i=0;i<n;i++)    {        if(vis[i])            continue;        else if(remain_len>=sticks[i])        {            vis[i]=true;            if(dfs(n_len,remain_len-sticks[i],num_stick-1))                return n_len;            vis[i]=false;            if(sticks[i]==remain_len||remain_len==n_len)                break;            while(sticks[i]==sticks[i+1])                i++;        }    }    return 0;}int main(){ while(~scanf("%d",&n)&&n) {     sum=0;     for(int i=0;i<n;i++)     {         scanf("%d",&sticks[i]);         sum+=sticks[i];     }     int ans=0;     sort(sticks,sticks+n,cmp);     for(int len=sticks[0];len<=sum;len++)     {         if(sum%len==0)         {             memset(vis,false,sizeof(vis));             ans=dfs(len,0,n);             if(ans)                break;         }     }     printf("%d\n",ans); } return 0;}