# ZeroJudge d539. 區間 MAX
[d539. 區間 MAX (題目連結)](https://zerojudge.tw/ShowProblem?problemid=d539)

**線段樹做法**
<font color="#00CE17">**AC**</font> **(0.3s, 12.1MB)**

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

const int N = 5e5 + 5;
int a[N], seg[N<<2];
int n;

void build(int l, int r, int v){
	if(l == r){
		seg[v] = a[l];
		return;
	}
	int m = (l + r) >> 1;
	build(l, m, v<<1);
	build(m+1, r, (v<<1)+1);
	seg[v] = max(seg[v<<1], seg[(v<<1)+1]);
}

int query(int ql, int qr, int l = 0, int r = n-1, int v = 1){
	if(ql > r || qr < l) return 0;
	if(ql <= l && qr >= r) return seg[v];
	int m = (l + r) >> 1;
	if(qr <= m) return query(ql, qr, l, m, v<<1);
	else if(ql > m) return query(ql, qr, m+1, r, (v<<1)+1); 
	return max(query(ql, m, l, m, v<<1), query(m+1, qr, m+1, r, (v<<1)+1));
}

signed main(){
	
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	
	cin>>n;
	for(int i=0; i<n; i++) cin>>a[i];
	build(0, n-1, 1);
	int m;
	cin>>m;
	while(m--){
		int a, b;
		cin>>a>>b;
		if(a > b) swap(a, b);
		a--, b--;
		cout<<query(a, b)<<'\n';
	}
	
	return 0;
}

###### 闕以諾 2022/7/6

###### tags: `C++` `ZeroJudge`