C++ 代码
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
const int N = 1000100;
int n, m;
int w[N];
struct Node {
int l, r;
int maxv;
}tr[4 * N];
void pushup(int u) {
tr[u].maxv = max(tr[u << 1].maxv, tr[u << 1 | 1].maxv);
}
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);
}
}
int query(int u, int l, int r) {
if (l <= tr[u].l && tr[u].r <= r) return tr[u].maxv;
int mid = tr[u].l + tr[u].r >> 1;
int maxv = INT32_MIN;
if (l <= mid) maxv = query(u << 1, l, r);
if (r > mid) maxv = max(maxv, query(u << 1 | 1, l, r));
return maxv;
}
void modify(int u, int x, int v) {
if (tr[u].l == tr[u].r) tr[u].maxv += v;
else {
int mid = tr[u].l + tr[u].r >> 1;
if (x <= mid) modify(u << 1, x, v);
else modify(u << 1 | 1, x, v);
pushup(u);
}
}
int main() {
scanf("%d %d", &n, &m);
for (int i = 1; i <= n; ++i) scanf("%d", &w[i]);
build(1, 1, n);
int x, y;
while (m--) {
scanf("%d %d", &x, &y);
printf("%d\n", query(1, x, y));
}
}