P1120 && UVA307 && POJ1011

排除等效冗余

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 #define rg register
 4 typedef long long ll;
 5 #define gmax(a,b) a=max(a,b)
 6 #define FOR(i,a,b) for(rg int i=a;i<=b;++i)
 7 #define gc pa==pb&&(pb=(pa=buf)+fread(buf,1,100000,stdin),pa==pb)?EOF:*pa++
 8 static char buf[100000],*pa(buf),*pb(buf);
 9 
10 inline int rd()
11 {
12   rg int x(0),w(1);
13   rg char c(gc);
14   while(c<'0' || c>'9')
15     {
16       if(c=='-') w=-1;
17       c=gc;
18     }
19   while(c>='0' && c<='9') x=x*10+c-48,c=gc;
20   return x*w;
21 }
22 
23 const int N=70;
24 int a[N];
25 bool vis[N];
26 int mx,cc,len,cnt,n;
27 
28 //p stick th    u now length    x:little stick th   
29 bool dfs(int p,int u,int x)
30 {
31   if(p>cnt) return 1;
32   if(u==len) return dfs(p+1,0,1);
33   int lf=0;
34   FOR(i,x,n)
35     if((!vis[i])&&a[i]+u<=len&&a[i]!=lf)
36       {
37     vis[i]=1;
38     if(dfs(p,a[i]+u,i+1)) return 1;
39     vis[i]=0;lf=a[i];
40     if(u+a[i]==len||u==0) return 0;
41       }
42   return 0;
43 }
44 
45 int main()
46 {
47   n=rd();
48   FOR(i,1,n) a[i]=rd(),cc+=a[i],gmax(mx,a[i]);
49   sort(a+1,a+n+1,greater<int>() );
50   //FOR(i,1,n) cout<<a[i]<<" ";cout<<endl;
51   for(len=mx;len<=cc;++len)
52     {
53       if(cc%len) continue;
54       cnt=cc/len;
55       memset(vis,0,sizeof(vis));
56       if(dfs(1,0,1)){cout<<len;break;}
57     }
58   return 0;
59 }