delete pics to save space

7.1167.cpp

@@ -0,0 +1,44 @@
+#include<cstdio>
+#include<cstring>
+#include<algorithm>
+using namespace std;
+int n,bu[60],res=17;
+struct Bus { int bg,jg,ti; };
+inline bool operator<(const Bus &a,const Bus &b) { return a.ti>b.ti; }
+Bus bus[1005]; int bc;
+inline bool check(int bg,int jg)
+{
+	for(int i=bg;i<60;i+=jg) if(!bu[i]) return false;
+	return true;
+}
+void dfs(int cho,int lst,int pos)
+{
+	if(cho+lst/bus[pos].ti>=res) return;
+	if(!lst) { res=min(res,cho); return; }
+	for(int i=pos;i<=bc;i++)
+	{
+		if(!check(bus[i].bg,bus[i].jg)) continue;
+		for(int j=bus[i].bg;j<60;j+=bus[i].jg) bu[j]--;
+		dfs(cho+1,lst-bus[i].ti,i);
+		for(int j=bus[i].bg;j<60;j+=bus[i].jg) bu[j]++;
+	}
+}
+int main()
+{
+#ifdef local
+	freopen("pro.in","r",stdin);
+#endif
+	scanf("%d",&n);
+	for(int i=0;i<n;i++) { int x; scanf("%d",&x); bu[x]++; }
+	for(int i=0;i<30;i++)
+		for(int j=i+1;i+j<60;j++)
+			if(check(i,j))
+			{
+				bus[++bc]=(Bus){i,j,0};
+				for(int k=i;k<60;k+=j) bus[bc].ti++;
+			}
+	sort(bus+1,bus+bc+1);
+	dfs(0,n,1);
+	printf("%d\n",res);
+	return 0;
+}