Created
September 7, 2020 13:59
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template <typename T> | |
class LazySegmentTree { | |
vector<T> data_; | |
vector<T> lazy_; | |
int size_; | |
void Eval(int k) { | |
if (lazy_[k] == 0) { | |
return; | |
} | |
if (k < size_ - 1) { | |
lazy_[k * 2 + 1] += lazy_[k]; | |
lazy_[k * 2 + 2] += lazy_[k]; | |
} | |
data_[k] += lazy_[k]; | |
lazy_[k] = 0; | |
} | |
void UpdateSub(int a, int b, T x, int k, int l, int r) { | |
Eval(k); | |
if (a <= l && r <= b) { | |
lazy_[k] += x; | |
Eval(k); | |
} else if (a < r && l < b) { | |
UpdateSub(a, b, x, k * 2 + 1, l, (l + r) / 2); | |
UpdateSub(a, b, x, k * 2 + 2, (l + r) / 2, r); | |
data_[k] = data_[k * 2 + 1] + data_[k * 2 + 2]; | |
} | |
} | |
T QuerySub(int a, int b, int k, int l, int r) { | |
Eval(k); | |
if (r <= a || b <= l) { | |
return 0; | |
} else if (a <= l && r <= b) { | |
return data_[k]; | |
} else { | |
return QuerySub(a, b, k * 2 + 1, l, (l + r) / 2) + | |
QuerySub(a, b, k * 2 + 2, (l + r) / 2, r); | |
} | |
} | |
public: | |
LazySegmentTree(int size) : data_(), lazy_() { | |
int n = 1; | |
while (size > n) { | |
n *= 2; | |
} | |
size_ = n; | |
data_.resize(n * 2 - 1); | |
lazy_.resize(n * 2 - 1); | |
fill(data_.begin(), data_.end(), 0); | |
fill(lazy_.begin(), lazy_.end(), 0); | |
} | |
void Update(int a, int b, T x) { UpdateSub(a, b, x, 0, 0, size_); } | |
T Query(int a, int b) { return QuerySub(a, b, 0, 0, size_); } | |
T Query(int a) { return Query(a, a + 1); } | |
}; |
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