delete pics to save space

2.307.cpp

@@ -0,0 +1,63 @@
+#include<cstdio>
+#include<cstring>
+const int N=70;
+int n,cnt,tot,maxn,minn,tm[N]; 
+bool ok;
+void dfs(int need,int sum,int goal,int maxlen)
+{
+	if(need==0)
+	{
+		printf("%d\n",goal);
+		ok=true;
+	}
+	if(sum==goal)//拼完了一根 
+	{
+		dfs(need-1,0,goal,maxn);
+		return;
+	}
+	for(int i=maxlen;i>=minn;i--)//用单调性确保不重复 
+		if(tm[i]&&i+sum<=goal)
+		{
+			tm[i]--;
+			dfs(need,sum+i,goal,i);
+			if(ok) return;
+			tm[i]++;
+			if(sum==0||sum+i==goal) break;
+		}
+	return;
+}
+int main()
+{
+#ifdef local
+	freopen("pro.in","r",stdin);
+#endif
+	while(scanf("%d",&n)==1&&n)
+	{
+		minn=N ;
+		int x;
+		cnt=tot=maxn=0;
+		memset(tm,0,sizeof(tm));
+		while(n--)
+		{
+			scanf("%d",&x);
+			if(x<=50)
+			{
+				cnt++;
+				tm[x]++;//用桶更方便 
+				tot+=x;
+				maxn=maxn>x?maxn:x;
+				minn=minn<x?minn:x;
+			}
+		}
+		x=tot/2;
+		ok=false;
+		for(int i=maxn;i<=x;i++)
+			if(tot%i==0)
+			{
+				dfs(tot/i,0,i,maxn);
+				if(ok) break;
+			}
+		if(!ok) printf("%d\n",tot);
+	}
+	return 0;
+}