线段树模板/带修线段树模板/c++
using namespace std;
template <typename T>
class SegTreeLazyRangeSet {
vector<T> tree, lazy;
vector<T> *arr;
int n, root, n4, end;
void maintain(int cl, int cr, int p) {
int cm = cl + (cr - cl) / 2;
if (cl != cr && lazy[p]) {
lazy[p * 2] = lazy[p];
lazy[p * 2 + 1] = lazy[p];
tree[p * 2] = lazy[p] * (cm - cl + 1);
tree[p * 2 + 1] = lazy[p] * (cr - cm);
lazy[p] = 0;
}
}
T range_sum(int l, int r, int cl, int cr, int p) {
if (l <= cl && cr <= r) return tree[p];
int m = cl + (cr - cl) / 2;
T sum = 0;
maintain(cl, cr, p);
if (l <= m) sum += range_sum(l, r, cl, m, p * 2);
if (r > m) sum += range_sum(l, r, m + 1, cr, p * 2 + 1);
return sum;
}
void range_set(int l, int r, T val, int cl, int cr, int p) {
if (l <= cl && cr <= r) {
lazy[p] = val;
tree[p] = (cr - cl + 1) * val;
return;
}
int m = cl + (cr - cl) / 2;
maintain(cl, cr, p);
if (l <= m) range_set(l, r, val, cl, m, p * 2);
if (r > m) range_set(l, r, val, m + 1, cr, p * 2 + 1);
tree[p] = tree[p * 2] + tree[p * 2 + 1];
}
void build(int s, int t, int p) {
if (s == t) {
tree[p] = (*arr)[s];
return;
}
int m = s + (t - s) / 2;
build(s, m, p * 2);
build(m + 1, t, p * 2 + 1);
tree[p] = tree[p * 2] + tree[p * 2 + 1];
}
public:
explicit SegTreeLazyRangeSet<T>(vector<T> v) {
n = v.size();
n4 = n * 4;
tree = vector<T>(n4, 0);
lazy = vector<T>(n4, 0);
arr = &v;
end = n - 1;
root = 1;
build(0, end, 1);
arr = nullptr;
}
void show(int p, int depth = 0) {
if (p > n4 || tree[p] == 0) return;
show(p * 2, depth + 1);
for (int i = 0; i < depth; ++i) putchar('\t');
printf("%d:%d\n", tree[p], lazy[p]);
show(p * 2 + 1, depth + 1);
}
T range_sum(int l, int r) { return range_sum(l, r, 0, end, root); }
void range_set(int l, int r, int val) { range_set(l, r, val, 0, end, root); }
};