ds/LineContainer.h

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• Last update: 2025-11-20 17:14:03+07:00

Verified with

• tests/Line_Add_Get_Min.test.cpp

Code

struct Line {
  mutable i64 k, m, p;
  bool operator<(const Line& o) const { return k < o.k; }
  bool operator<(i64 x) const { return p < x; }
};

struct LineContainer : multiset<Line, less<>> {
  // (for lds, use inf = 1/.0, div(a,b) = a/b)
  static const i64 inf = LLONG_MAX;
  i64 div(i64 a, i64 b) {  // floored division
    return a / b - ((a ^ b) < 0 && a % b);
  }
  bool isect(iterator x, iterator y) {
    if (y == end()) return x->p = inf, 0;
    if (x->k == y->k)
      x->p = x->m > y->m ? inf : -inf;
    else
      x->p = div(y->m - x->m, x->k - y->k);
    return x->p >= y->p;
  }
  void add(i64 k, i64 m) {
    auto z = insert({k, m, 0}), y = z++, x = y;
    while (isect(y, z)) z = erase(z);
    if (x != begin() && isect(--x, y)) isect(x, y = erase(y));
    while ((y = x) != begin() && (--x)->p >= y->p) isect(x, erase(y));
  }
  i64 query(i64 x) { // return max
    assert(!empty());
    auto l = *lower_bound(x);
    return l.k * x + l.m;
  }
};

#line 1 "ds/LineContainer.h"
struct Line {
  mutable i64 k, m, p;
  bool operator<(const Line& o) const { return k < o.k; }
  bool operator<(i64 x) const { return p < x; }
};

struct LineContainer : multiset<Line, less<>> {
  // (for lds, use inf = 1/.0, div(a,b) = a/b)
  static const i64 inf = LLONG_MAX;
  i64 div(i64 a, i64 b) {  // floored division
    return a / b - ((a ^ b) < 0 && a % b);
  }
  bool isect(iterator x, iterator y) {
    if (y == end()) return x->p = inf, 0;
    if (x->k == y->k)
      x->p = x->m > y->m ? inf : -inf;
    else
      x->p = div(y->m - x->m, x->k - y->k);
    return x->p >= y->p;
  }
  void add(i64 k, i64 m) {
    auto z = insert({k, m, 0}), y = z++, x = y;
    while (isect(y, z)) z = erase(z);
    if (x != begin() && isect(--x, y)) isect(x, y = erase(y));
    while ((y = x) != begin() && (--x)->p >= y->p) isect(x, erase(y));
  }
  i64 query(i64 x) { // return max
    assert(!empty());
    auto l = *lower_bound(x);
    return l.k * x + l.m;
  }
};

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