HDU 1754 Java

退役后学java...

裸线段树

//By SiriusRen
import java.util.*;
import java.math.*;
public class Main{
    public static void build(int l,int r,int pos,int []tree,int []score){
        if(l==r){tree[pos]=score[l];return;}
        int mid=(l+r)>>1,lson=pos<<1,rson=pos<<1|1;
        build(l,mid,lson,tree,score);build(mid+1,r,rson,tree,score);
        tree[pos]=Math.max(tree[lson],tree[rson]);
    }
    public static void insert(int l,int r,int pos, int num,int wei,int []tree){
        if(l==r){tree[pos]=wei;return;}
        int mid=(l+r)>>1,lson=pos<<1,rson=pos<<1|1;
        if(mid<num)insert(mid+1,r,rson,num,wei,tree);
        else if(mid>=num)insert(l,mid,lson,num,wei,tree);
        tree[pos]=Math.max(tree[lson],tree[rson]);
    }
    public static int query(int l,int r,int pos,int L,int R,int []tree){
        if(l>=L&&r<=R)return tree[pos];
        int mid=(l+r)>>1,lson=pos<<1,rson=pos<<1|1;
        if(mid<L)return query(mid+1,r,rson,L,R,tree);
        else if(mid>=R)return query(l,mid,lson,L,R,tree);
        else return Math.max(query(l,mid,lson,L,R,tree),query(mid+1,r,rson,L,R,tree));
    }
    public static void main(String args[]){
        int []score=new int[200005];
        int []Tree=new int[3500000];
        Scanner in=new Scanner(System.in);
        while(in.hasNextInt()){
            int n=in.nextInt(),m=in.nextInt();
            for(int i=1;i<=n;i++)score[i]=in.nextInt();
            build(1,n,1,Tree,score);
            for(int i=1;i<=m;i++){
                String p=in.next();
                if(p.equals("Q")){
                    int jyx=in.nextInt(),jyy=in.nextInt();
                    int jy=query(1,n,1,jyx,jyy,Tree);
                    System.out.println(jy);
                }
                else{
                    int jyx=in.nextInt(),jyy=in.nextInt();
                    insert(1,n,1,jyx,jyy,Tree);
                }
            }
        }
    }
}