Single point modification, query the maximum value of the midpoint of the interval
Topic link: acwing1275 maximum
#include <algorithm>
#include <cstdio>
#include <iostream>
using namespace std;
const int N = 200010;
int m, p;
struct Node {
int l, r;
int v; // [l,r]最大值
} tr[4 * N];
// 由子节点的信息，来计算父节点的信息
void pushup(int u) {
tr[u].v = max(tr[u << 1].v, tr[u << 1 | 1].v); }
void build(int u, int l, int r) {
tr[u] = {
l, r};
if (l == r) return;
int mid = l + r >> 1;
build(u << 1, l, mid), build(u << 1 | 1, mid + 1, r);
}
// 查询l,r最大值
int query(int u, int l, int r) {
// 树中节点，已经被完全包含在[l, r]中了
if (tr[u].l >= l && tr[u].r <= r) return tr[u].v;
int mid = tr[u].l + tr[u].r >> 1;
int v = 0;
if (l <= mid) v = query(u << 1, l, r);
if (r > mid) v = max(v, query(u << 1 | 1, l, r));
return v;
}
// 修改x位位置值为v
void modify(int u, int x, int v) {
if (tr[u].l == x && tr[u].r == x) {
tr[u].v = v;
return;
}
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);
}
// 输入代码
int main() {
scanf("%d%d", &m, &p);
int n = 0, last = 0;
build(1, 1, m);
int x;
char op[2];
while (m--) {
scanf("%s%d", op, &x);
if (*op == 'Q') {
last = query(1, n - x + 1, n);
printf("%d\n", last);
} else {
modify(1, n + 1, (last + x) % p);
n++;
}
}
return 0;
}
Single-point modification, query the largest continuous sub-segment and
Subject: AcWing 245. Can you answer these questions?
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
const int N = 500010;
int n, m;
int w[N];
struct Node
{
int l, r;
int sum, lmax, rmax, tmax;
}tr[N * 4];
void pushup(Node &u, Node &l, Node &r)
{
u.sum = l.sum + r.sum;
u.lmax = max(l.lmax, l.sum + r.lmax);
u.rmax = max(r.rmax, r.sum + l.rmax);
u.tmax = max(max(l.tmax, r.tmax), l.rmax + r.lmax);
}
void pushup(int u)
{
pushup(tr[u], tr[u << 1], tr[u << 1 | 1]);
}
void build(int u, int l, int r)
{
if (l == r) tr[u] = {
l, r, w[r], w[r], w[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);
}
}
void modify(int u, int x, int v)
{
if (tr[u].l == x && tr[u].r == x) tr[u] = {
x, x, v, v, v, 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);
}
}
Node query(int u, int l, int r)
{
if (tr[u].l >= l && tr[u].r <= r) return tr[u];
else
{
int mid = tr[u].l + tr[u].r >> 1;
if (r <= mid) return query(u << 1, l, r);
else if (l > mid) return query(u << 1 | 1, l, r);
else
{
auto left = query(u << 1, l, r);
auto right = query(u << 1 | 1, l, r);
Node res;
pushup(res, left, right);
return res;
}
}
}
int main()
{
scanf("%d%d", &n, &m);
for (int i = 1; i <= n; i ++ ) scanf("%d", &w[i]);
build(1, 1, n);
int k, x, y;
while (m -- )
{
scanf("%d%d%d", &k, &x, &y);
if (k == 1)
{
if (x > y) swap(x, y);
printf("%d\n", query(1, x, y).tmax);
}
else modify(1, x, y);
}
return 0;
}