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69 lines
1.5 KiB
69 lines
1.5 KiB
#include <cstdio>
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#include <cstring>
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#include <algorithm>
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#include <iostream>
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using namespace std;
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const int N = 1e6 + 10;
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typedef long long LL;
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int n, m;
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int a[N];
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struct Node {
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int l, r;
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int lmax;
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int rmax;
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int tmax;
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int sum;
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} tr[N << 2];
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void calc(Node &u, Node &l, Node &r) {
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u.sum = l.sum + r.sum;
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u.lmax = max(l.lmax, l.sum + r.lmax);
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u.rmax = max(r.rmax, r.sum + l.rmax);
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u.tmax = max({l.tmax, r.tmax, l.rmax + r.lmax});
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}
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void pushup(int u) {
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calc(tr[u], tr[u << 1], tr[u << 1 | 1]);
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}
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void build(int u, int l, int r) {
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tr[u] = {l, r, 0, 0, 0, 0}; // 无初始值
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if (l == r) {
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tr[u].sum = tr[u].lmax = tr[u].rmax = tr[u].tmax = a[l];
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return;
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}
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int mid = (l + r) >> 1;
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build(u << 1, l, mid), build(u << 1 | 1, mid + 1, r);
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pushup(u);
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}
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Node query(int u, int l, int r) {
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if (l <= tr[u].l && r >= tr[u].r) return tr[u];
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int mid = tr[u].l + tr[u].r >> 1;
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if (l > mid) return query(u << 1 | 1, l, r);
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if (r <= mid) return query(u << 1, l, r);
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Node a = query(u << 1, l, r), b = query(u << 1 | 1, l, r), res;
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calc(res, a, b);
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return res;
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}
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int main() {
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ios::sync_with_stdio(false), cin.tie(0);
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cin >> n;
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for (int i = 1; i <= n; i++) cin >> a[i];
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build(1, 1, n);
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cin >> m;
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int x, y;
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while (m--) {
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cin >> x >> y;
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printf("%d\n", query(1, x, y).tmax);
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}
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return 0;
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} |