UVA 10534 Wavio Sequence(LIS O(nlogn))

p数组需要初始化。

#include<iostream>#include<cstdio>#include<cstring>#include<algorithm>using namespace std;const int maxn=10000+10;int s[maxn],p[maxn],f1[maxn],f2[maxn];int main(){    int n;    while(scanf("%d",&n)!=EOF)    {        for(int i=1;i<=n;i++) scanf("%d",&s[i]);        memset(p,0x7f,sizeof(p));p[0]=0;        int len=0;        for(int i=1;i<=n;i++)        {            int pos=(int)(lower_bound(p+1,p+1+n,s[i])-p);            len=max(len,pos);            f1[i]=len;            p[pos]=s[i];        }        len=0;        memset(p,0x7f,sizeof(p));p[0]=0;        for(int i=n;i>=1;i--)        {            int pos=(int)(lower_bound(p+1,p+1+n,s[i])-p);            len=max(len,pos);            f2[i]=len;            p[pos]=s[i];        }        int maxlen=0;        for(int i=1;i<=n;i++) if(f1[i]==f2[i]) maxlen=max(maxlen,f1[i]+f2[i]-1);        cout<<maxlen<<endl;    }    return 0;}