最长上升子序列III--利用二分优化至nlogn

#include<iostream>
#include<algorithm>
using namespace std;
const int N=100010;
int n;
int a[N],q[N];

int main(void){
    cin>>n;
    for(int i=0; i<n; i++)cin>>a[i];
    int len=0;
    q[0]=-2e9;
    for(int i=0;i<n;i++){
        int l=0,r=len;
        while(l<r){
            int mid=l+r+1>>1;
            if(q[mid]<a[i])l=mid;
            else r=mid-1;
        }
        len=max(len,r+1);
        q[r+1]=a[i];
    }
    cout<<len<<endl;
    return 0;
}