RMQ能干的，线段树凭什么不能！！

经过了无数的卡常数，终于AC了。

#pragma GCC diagnostic error "-std=c++11"
#pragma GCC target("avx")
#pragma GCC optimize(3)
#pragma GCC optimize("Ofast")
#pragma GCC optimize("inline")
#pragma GCC optimize("-fgcse")
#pragma GCC optimize("-fgcse-lm")
#pragma GCC optimize("-fipa-sra")
#pragma GCC optimize("-ftree-pre")
#pragma GCC optimize("-ftree-vrp")
#pragma GCC optimize("-fpeephole2")
#pragma GCC optimize("-ffast-math")
#pragma GCC optimize("-fsched-spec")
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("-falign-jumps")
#pragma GCC optimize("-falign-loops")
#pragma GCC optimize("-falign-labels")
#pragma GCC optimize("-fdevirtualize")
#pragma GCC optimize("-fcaller-saves")
#pragma GCC optimize("-fcrossjumping")
#pragma GCC optimize("-fthread-jumps")
#pragma GCC optimize("-funroll-loops")
#pragma GCC optimize("-fwhole-program")
#pragma GCC optimize("-freorder-blocks")
#pragma GCC optimize("-fschedule-insns")
#pragma GCC optimize("inline-functions")
#pragma GCC optimize("-ftree-tail-merge")
#pragma GCC optimize("-fschedule-insns2")
#pragma GCC optimize("-fstrict-aliasing")
#pragma GCC optimize("-fstrict-overflow")
#pragma GCC optimize("-falign-functions")
#pragma GCC optimize("-fcse-skip-blocks")
#pragma GCC optimize("-fcse-follow-jumps")
#pragma GCC optimize("-fsched-interblock")
#pragma GCC optimize("-fpartial-inlining")
#pragma GCC optimize("no-stack-protector")
#pragma GCC optimize("-freorder-functions")
#pragma GCC optimize("-findirect-inlining")
#pragma GCC optimize("-fhoist-adjacent-loads")
#pragma GCC optimize("-frerun-cse-after-loop")
#pragma GCC optimize("inline-small-functions")
#pragma GCC optimize("-finline-small-functions")
#pragma GCC optimize("-ftree-switch-conversion")
#pragma GCC optimize("-foptimize-sibling-calls")
#pragma GCC optimize("-fexpensive-optimizations")
#pragma GCC optimize("-funsafe-loop-optimizations")
#pragma GCC optimize("inline-functions-called-once")
#pragma GCC optimize("-fdelete-null-pointer-checks")
#include<bits/stdc++.h>
using namespace std;
const int N = 100010;
int n, m;
int w[N];
struct Node
{
    int l, r;
    int maxn;
}tr[N * 4];
inline void pushup(int u)
{
    tr[u].maxn = max(tr[u << 1].maxn, tr[u << 1 | 1].maxn);
}
inline void build(int u, int l, int r)
{
    if(l == r) tr[u] = {l, r, w[r]};
    else
    {
        tr[u] = {l, r};
        int mid = (l + r) >> 1;
        build(u << 1, l, mid);
        build(u << 1 | 1, mid + 1, r);
        pushup(u);
    }
}
inline int query(int u, int l, int r)
{
    if(tr[u].l >= l && tr[u].r <= r) return tr[u].maxn;
    int mid = tr[u].l + tr[u].r >> 1;
    int ans = -0x3f3f3f3f;
    if(r <= mid) ans = max(ans, query(u << 1, l, r));
    else if(l > mid) ans = max(ans, query(u << 1 | 1, l, r));
    else 
    {
        int left = query(u << 1, l, r);
        int right = query(u << 1 | 1, l, r);
        ans = max(ans, max(left, right));
    }
    return ans;
}
int main()
{
    cin >> n >> m;
    for(int i = 1; i <= n; i ++) scanf("%d", &w[i]);
    build(1, 1, n);
    while(m --)
    {
        int x, y;
        scanf("%d%d", &x, &y);
        printf("%d\n", query(1, x, y));
    }
}