UVA 10534 Wavio Sequence

　　正反两个方向各求一遍LIS（需要O(nlogn)算法），枚举中心。

//10534 Wavio Sequence Accepted C++ 0.096 2012-11-14 10:34:30#include<cstdio>#include<cstring>#include<algorithm>using namespace std;const int MAXN = 10000+5;int N, a[MAXN];int d[2][MAXN], f[MAXN];int main(){while (scanf("%d", &N) != EOF){int maxi = 0;for (int i = 1; i <= N; i++){scanf("%d", &a[i]);int x = lower_bound(f+1, f+1+maxi, a[i])-f;maxi = max(maxi, x);f[x] = a[i];d[0][i] = x;}maxi = 0;for (int i = N; i >= 1; i--){int x = lower_bound(f+1, f+1+maxi, a[i])-f;maxi = max(maxi, x);f[x] = a[i];d[1][i] = x;}int ans = 0;for (int i = 1; i <= N; i++)ans = max(ans, min(d[0][i], d[1][i])*2-1);printf("%d\n", ans);}return 0;}