[NOI.AC]DELETE(LIS)

 

 

解析：

代碼：

#include<bits/stdc++.h>
using namespace std;
#define ll long long 
#define rint register int

inline int read(){
    int x=0,f=0;char ch=getchar();
    while(!isdigit(ch)) f=(ch==45),ch=getchar();
    while( isdigit(ch)) x=(x<<1)+(x<<3)+(ch^48),ch=getchar();
    return f?(~x+1):x;
}

#define man 1000050

int n,k,ans;
int a[man],f[man];
int main(){
    n=read();k=read();
    for (int i=1;i<=n;i++) a[i]=read();
    for (int i=1;i<=n;i++){
        for (int j=n-k;j>=1;j--){
            f[j]=max(f[j],f[j-1]+(j==a[i]));
        }
    }
    printf("%d",f[n-k]);
    return 0;
}

100分：

#include<bits/stdc++.h>
using namespace std;
#define ll long long 
#define rint register int

inline int read(){
    int x=0,f=0;char ch=getchar();
    while(!isdigit(ch)) f=(ch==45),ch=getchar();
    while( isdigit(ch)) x=(x<<1)+(x<<3)+(ch^48),ch=getchar();
    return f?(~x+1):x;
}

#define man 1000050

int a[man],n,k;
struct node{    int x,y;}c[man];

int b[man],ans=0;
inline void update(int x,int val){
    while(x<=n){
        b[x]=max(b[x],val);
        x+=(x&(-x));
    }
}

inline int query(int x){
    int maxn=0;
    while(x>0){
        maxn=max(maxn,b[x]);
        x-=(x&(-x));
    }
    return maxn;
}

int cmp(node a,node b){
    if(a.x<b.x) return 1;
    if(a.x==b.x&&a.y<b.y) return 1;
    return 0;
}

int main(){
    n=read();k=read();
    for(rint i=1;i<=n;i++){
        a[i]=read();
        c[i]=(node){i-a[i],a[i]};
    }
    sort(c+1,c+1+n,cmp);
    for(rint i=1;i<=n;i++){
        if(c[i].x<0||c[i].y>n-k||c[i].x>k) continue;
        int cnt=query(c[i].y-1)+1;
        ans=max(ans,cnt);
        update(c[i].y,cnt);
    }
    printf("%d\n",min(ans,n-k));
    return 0;
}