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P4513.cpp
68 lines (68 loc) · 1.44 KB
/
P4513.cpp
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#include <bits/stdc++.h>
using namespace std;
int n, m;
struct Node{
int sm, lm, rm, mx;
Node(int sm=0, int lm=0, int rm=0, int mx=0): sm(sm), lm(lm), rm(rm), mx(mx) {
}
}t[1048577];
int a[500020];
Node operator+(const Node&a, const Node&b) {
return Node(a.sm+b.sm, max(a.lm, a.sm+b.lm), max(a.rm+b.sm, b.rm), max(a.rm+b.lm, max(a.mx, b.mx)));
}
void build(int x, int l, int r) {
if (l == r) {
t[x] = Node(a[l], a[l], a[l], a[l]);
return;
}
int mid = (l + r) / 2;
build(x * 2, l, mid);
build(x * 2 + 1, mid + 1, r);
t[x] = t[x * 2] + t[x * 2 + 1];
}
void change(int x, int l, int r, int p, int v) {
if (l == r) {
t[x] = Node(v, v, v, v);
return;
}
int mid = (l + r) / 2;
if (p > mid) {
change(2 * x + 1, mid + 1, r, p, v);
} else {
change(2 * x, l, mid, p, v);
}
t[x] = t[x * 2] + t[x * 2 + 1];
}
Node query(int x, int l, int r, int L, int R) {
if (L <= l && r <= R) {
return t[x];
}
int mid = (l + r) / 2;
if (R <= mid) {
return query(x * 2, l, mid, L, R);
}
if (L > mid) {
return query(x * 2 + 1, mid + 1, r, L, R);
}
return query(x * 2, l, mid, L, R) + query(x * 2 + 1, mid + 1, r, L, R);
}
int main() {
scanf("%d%d", &n, &m);
for (int i = 1; i <= n; i++) {
scanf("%d", &a[i]);
}
build(1, 1, n);
for (int i = 0; i < m; i++) {
int o, x, y;
scanf("%d%d%d", &o, &x, &y);
if (o == 1) {
if (x > y) {
swap(x, y);
}
printf("%d\n", query(1, 1, n, x, y).mx);
} else {
change(1, 1, n, x, y);
}
}
return 0;
}