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Segment Tree.cpp
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Segment Tree.cpp
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#include<bits/stdc++.h>
using namespace std;
const int N = 3e5 + 9;
int a[N];
struct ST {
int t[4 * N];
static const int inf = 1e9;
ST() {
memset(t, 0, sizeof t);
}
void build(int n, int b, int e) {
if (b == e) {
t[n] = a[b];
return;
}
int mid = (b + e) >> 1, l = n << 1, r = l | 1;
build(l, b, mid);
build(r, mid + 1, e);
t[n] = max(t[l], t[r]);
}
void upd(int n, int b, int e, int i, int x) {
if (b > i || e < i) return;
if (b == e && b == i) {
t[n] = x;
return;
}
int mid = (b + e) >> 1, l = n << 1, r = l | 1;
upd(l, b, mid, i, x);
upd(r, mid + 1, e, i, x);
t[n] = max(t[l], t[r]);
}
int query(int n, int b, int e, int i, int j) {
if (b > j || e < i) return -inf;
if (b >= i && e <= j) return t[n];
int mid = (b + e) >> 1, l = n << 1, r = l | 1;
int L = query(l, b, mid, i, j);
int R = query(r, mid + 1, e, i, j);
return max(L, R);
}
}t;
int32_t main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
return 0;
}