朴素线段树为什么只有9分

#include <bits/stdc++.h>
using namespace std;
inline void read(int& qin){
    int qout = 0, w = 1;
    char ch = getchar();
    while(ch < '0' || ch > '9'){
        if(ch == '-') w = -1;
        ch = getchar();
    }
    while(ch >= '0' && ch <= '9'){
        qout = qout * 10 + ch - '0';
        ch = getchar();
    }
    qin = qout * w;
}
inline void write(int x){
    if(x < 0) putchar('-'),x = -x;
    if(x > 9) write(x/10);
    putchar(x % 10 + '0');
}
int n,m;
int now[500050],t[500050 * 4];
inline int ls(int p){return p<<1;}
inline int rs(int p){return p<<1|1;}
void push_up(int p) {t[p] = max(t[ls(p)],t[rs(p)]);}
void build(int p,int l,int r){
    if(l == r){
        t[p] = now[l];
        return;
    }
    int mid = (l + r) >> 1;
    build(ls(p),l,mid);
    build(rs(p),mid+1,r);
    push_up(p);
}
void move(int p,int l,int r,int cnt,int op){
    if(l == r){
        t[p] = cnt;
        return;
    }
    int mid = (l + r) >> 1;
    if(op <= mid) move(ls(p),l,mid,cnt,op);
    else move(rs(p),mid+1,r,cnt,op);
    push_up(p);
}
int check(int lc,int rc,int p,int l,int r){
    int res = INT_MIN;
    if(lc <= l && r <= rc) return t[p];
    int mid = (l + r) >> 1;
    if(lc <= mid) res = max(res,check(lc,rc,ls(p),l,mid));
    if(rc > mid) res = max(res,check(lc,rc,rs(p),mid+1,r));
    return res;
}
int main(){
    cin>>n>>m;
    for(int i=1;i<=n;i++) read(now[i]);
    build(1,1,n);
    int k,a,b,l,r;
    for(int i=1;i<=m;i++){
        read(k),read(a),read(b);
        if(k == 1){
            l = min(a,b),r = max(a,b);
            write(check(l,r,1,1,n));
            putchar('\n');
        }
        else move(1,1,n,b,a);
    }
    return 0;
}