【模板】珂朵莉树

posted on 2021-04-02 20:38:49 | under 学术 | source

这个东西本身不常用，但是这个维护连续段的写法很常用。

标签：暴力、数据结构、std::set

#include <set>
template <class T = long long>
class ODT {
 private:
  struct node {
    int l, r;
    mutable T v;
    node(int l, int r = -1, T v = 0) : l(l), r(r), v(v) {}
    bool operator<(const node &b) const { return l < b.l; }
    friend int rangelen(const node &a) { return a.r - a.l + 1; }
  };
  std::set<node> s;
  typedef typename std::set<node>::iterator IT;

 public:
  void init(int n, int *a) {
    s.insert(node(n + 1, n + 1));
    for (int i = 1; i <= n; i++) s.insert(node(i, i, a[i]));
  }
  IT split(int pos) {
    IT it = s.lower_bound(node(pos));
    if (it != s.end() && it->l == pos) return it;
    --it;
    int l = it->l, r = it->r;
    T v = it->v;
    s.erase(it);
    s.insert(node(l, pos - 1, v));
    return s.insert(node(pos, r, v)).first;
  }
  void assign(int l, int r, T v = 0) {
    IT R = split(r + 1), L = split(l);
    s.erase(L, R);
    s.insert(node(l, r, v));
  }
//template <class function>
//void work(int l, int r, function work) {
//  IT R = split(r + 1), L = split(l);
//  for (IT it = L; it != R; ++it) work();
//}
};