-
using T = ...
-
using L = ...
-
T t_ide()
-
L l_ide()
-
T ope(const T& a, const T& b)
-
L lazy_ope(const L& a, const L& b)
-
T effect(const T& t, const L& l, const i64 len)
-
lazy_segment_tree(const vector<T>& init)
init
からLazy Segment Treeを構築する
- \( O(n) \)
-
update(i64 a, i64 b, L lx)
[a, b)
番目の要素に作用lx
をする
- \( O(\log n) \)
-
sum(i64 a, i64 b)
[a, b)
の総和を求める
- \( O(\log n) \)
#include <vector>
#include <set>
#include <iostream>
using i64 = long long;
struct lazy_segment_tree {
using T = i64;
using L = i64;
static inline T t_ide() { return (1LL << 31) - 1; }
static inline L l_ide() { return (1LL << 31) - 1; }
static inline T ope(const T& a, const T& b) { return std::min(a, b); }
static inline L lazy_ope(const L& a, const L& b) { return b; }
static inline T effect(const T& t, const L& l) { return l; }
int n, h;
std::vector<T> node;
std::vector<L> lazy;
std::vector<bool> flag;
lazy_segment_tree(int N) {
n = 1;
h = 1;
while(n < N) n <<= 1, h++;
node.resize(n << 1, t_ide());
lazy.resize(n << 1, l_ide());
flag.resize(n << 1, false);
}
lazy_segment_tree(const std::vector<T>& init) {
n = 1;
h = 1;
while(n < init.size()) n <<= 1, h++;
node.resize(n << 1, t_ide());
lazy.resize(n << 1, l_ide());
flag.resize(n << 1, false);
for(int i = 0;i < init.size();i++) node[i + n] = init[i];
for(int i = n; i --> 1;) node[i] = ope(node[(i << 1)], node[(i << 1) + 1]);
}
inline void eff(int k, L x) {
if(k < n << 1) {
lazy[k] = lazy_ope(lazy[k], x);
flag[k] = true;
}
}
inline T eval(int k) const { return flag[k] ? effect(node[k], lazy[k]) : node[k]; }
inline void push(int k) {
if(flag[k]) {
node[k] = eval(k);
eff(k << 1, lazy[k]);
eff((k << 1) | 1, lazy[k]);
lazy[k] = l_ide();
flag[k] = false;
}
}
inline void infuse(int k) {
k = k >> __builtin_ctz(k);
while((k >>= 1)) node[k] = ope(eval(k << 1), eval((k << 1) + 1));
}
inline void infiltrate(int k) {
if(k == n << 1) return;
int kc = __builtin_ctz(k);
for(int i = h; i --> kc;) push(k >> i);
}
inline void infiltrate(int l, int r) {
if(r == n << 1) infiltrate(l);
else {
int hh = h;
int x = l ^ r;
for(; !(x >> --hh);) push(l >> hh);
int lc = __builtin_ctz(l);
for(int i = hh + 1; i --> lc;) push(l >> i);
int rc = __builtin_ctz(r);
for(int i = hh + 1; i --> rc;) push(r >> i);
}
}
void update(int a, int b, L x) {
int l = a + n;
int r = b + n;
infiltrate(l, r);
while(l < r) {
if(l & 1) eff(l++, x);
if(r & 1) eff(--r, x);
l >>= 1;
r >>= 1;
}
infuse(a + n);
infuse(b + n);
}
T sum(int l, int r) {
l += n;
r += n;
infiltrate(l, r);
T lx = t_ide();
T rx = t_ide();
while(l < r) {
if(l & 1) lx = ope(lx, eval(l++));
if(r & 1) rx = ope(eval(--r), rx);
l >>= 1;
r >>= 1;
}
return ope(lx, rx);
}
};