delete pics to save space

2.10534.cpp

@@ -0,0 +1,35 @@
+#include<cstdio>
+#include<algorithm>
+using namespace std;
+const int oo=1e9;
+const int maxn=10005;
+int n;
+int a[maxn],dp[maxn],f1[maxn],f2[maxn];
+void DP(int *f)
+{
+	fill(dp,dp+maxn,oo);
+	for(int i=0;i<n;i++)
+	{
+		int k=lower_bound(dp+1,dp+n+1,a[i])-dp;
+		dp[k]=a[i];
+		f[i]=k;
+	}
+}
+int main()
+{
+#ifdef local
+	freopen("pro.in","r",stdin);
+#endif
+	while(scanf("%d",&n)==1)
+	{
+		for(int i=0;i<n;i++) scanf("%d",&a[i]);
+		DP(f1);
+		reverse(a,a+n);
+		DP(f2);
+		int res=0;
+		for(int i=0;i<n;i++)
+			res=max(res,min(f1[i],f2[n-i-1])*2-1);
+		printf("%d\n",res);
+	}
+	return 0;
+}