pku1011

 

#include <stdio.h>
#include <stdlib.h>
#include <memory.h>

int totLen,len,maxL,n,i,k;
int s[64];
int used[64];

int cmp(const void * a, const void * b)...{ 
    return (*(int *)b) - (*(int *)a);
}

bool Search(int times,int rest,int pos)...{
    int flag=0;
    if(rest == len) flag = 1;
    if(times==totLen/len)
        return 1;
    int i;//尽量用局部变量
    for(i=pos;i<n;i++)...{
        if(used[i])
            continue;
        if(s[i]==rest)...{
            used[i]=1;
            if(Search(times+1,len,0))
                return 1;
            used[i]=0;//大的刚好匹配的s[i]不能填入,不必再考虑更小的了.因若s[j]+s[k](j,k<i)
            //填入前面的棍(s[j]+s[k]==s[i])、s[i]填入后面的棍可行,则s[j]+s[k]与s[i]调换肯定也ok
            return 0;
        }
        else if(s[i]<rest)...{
                used[i]=1;
                if( Search(times,rest-s[i],i+1) )return 1;
                used[i]=0;
                if(flag) return 0; //因为rest==len的情况下(新棍开始),s[i]一定要
                //被用上(s[i]是从0开始第一个未被用过的小棒),但找不到解，说明此时len不是解
                while(s[i+1]==s[i])i++;
            }
    }
    return 0;
}

int main()
...{
    int len1;
    while( scanf("%d",&n),n>0 )...{
        memset(s,0,sizeof(s));
        maxL=-1,totLen=0;
        for(i=0;i<n;i++)...{
            scanf("%d",&s[i]);
            totLen+=s[i];
            if(s[i]>maxL)
                maxL=s[i];
        }
        qsort(s,n,sizeof(s[0]),cmp);
        for(len1=maxL;len1<=totLen;len1++)...{
            if(totLen%len1!=0)
                continue;
            len=len1;
            memset(used,0,sizeof(used));
            if(Search(1,len1,0))...{
                printf("%d ",len1);
                break;
            }
        }
    }
    return 1;
}