LIS算法

LIS（Longest Increasing Subsequence）最长上升（不下降）子序列。

1. O(n^2)

 #include<cstdio>
 #include<algorithm>
 using namespace std;

 int n,ans;
 int a[],d[];

 int main(){
     scanf("%d",&n);
     for(int i=;i<=n;++i)scanf("%d",&a[i]);
     for(int i=;i<=n;++i){
         d[i]=;
         for(int j=;j<i;++j)
             if(a[i]>a[j]&&d[i]+>d[j])d[i]=d[j]+;
     }
     for(int i=;i<=n;++i)ans=max(ans,d[i]);
     printf("%d",ans);
     return ;
 } 

2. O(n logn)

 #include<cstdio>
 int n;
 int a[];
 int stack[],top;

 int main(){
     scanf("%d",&n);
     for(int i=;i<=n;++i)scanf("%d",&a[i]);
     stack[++top]=a[];
     for(int i=;i<=n;++i){
         if(a[i]>stack[top])stack[++top]=a[i];
         else {
             int l=,r=top;
             while(l<=r){
                 int mid=l+r>>;
                 if(stack[mid]<a[i])l=mid+;
                 else r=mid-;
             }
             stack[r]=a[i];
         }
     }
     printf("%d",top);
     return ;
 }