feat: mono_{stack,queue} & hoverline

config.yml

@@ -113,6 +113,12 @@ notebook:
       code_ext: hpp
       test_ext: cpp
     ds:
+    - mono_stack: 单调栈
+      code_ext: hpp
+      test_ext: cpp
+    - mono_queue: 单调队列
+      code_ext: hpp
+      test_ext: cpp
     - bt_trv: 树结点常见遍历操作
       code_ext: hpp
       test_ext: cpp
@@ -455,6 +461,9 @@ notebook:
     - lis: 最长上升子序列
       code_ext: hpp
       test_ext: cpp
+    - hoverline: 悬线法
+      code_ext: hpp
+      test_ext: cpp
     - lcs_circ: 环序列的最长公共子序列长度
       code_ext: hpp
       test_ext: cpp

src/code/ds/mono_queue.hpp

@@ -0,0 +1,29 @@
+#ifndef TIFALIBS_DS_MONO_QUEUE
+#define TIFALIBS_DS_MONO_QUEUE
+
+#include "../util/util.hpp"
+
+namespace tifa_libs::ds {
+
+template <class T, class Comp = std::less<T>>
+class mono_queue {
+  static CEXP Comp compare{};
+
+  const u32 k;
+  u32 i;
+  std::deque<std::pair<T, u32>> q;
+
+ public:
+  CEXPE mono_queue(u32 k) NE : k{k}, i{0} { assert(k > 0); }
+  // @return minimum of last k (at most) pushed elements
+  CEXP T CR push(cT_(T) x) NE {
+    if (!q.empty() && q.front().second + k == i) q.pop_front();
+    while (!q.empty() && compare(x, q.back().first)) q.pop_back();
+    q.emplace_back(x, i++);
+    return q.front().first;
+  }
+};
+
+}  // namespace tifa_libs::ds
+
+#endif

src/code/ds/mono_stack.hpp

@@ -0,0 +1,41 @@
+#ifndef TIFALIBS_DS_MONO_STACK
+#define TIFALIBS_DS_MONO_STACK
+
+#include "../util/util.hpp"
+
+namespace tifa_libs::ds {
+
+template <class T, class Comp = std::less<T>>
+class mono_stack {
+  static CEXP Comp compare{};
+
+  vec<T> s;
+  template <bool use_bf = false>
+  CEXP auto find_(cT_(T) x) NE {
+    if CEXP (use_bf) {
+      auto it = s.rbegin();
+      while (it != s.rend() && compare(x, *it)) ++it;
+      return (--it).base();
+    } else return upper_bound(s, x, compare);
+  }
+
+ public:
+  CEXPE mono_stack() NE = default;
+
+  template <bool use_bf = false>
+  CEXP void pop_greater(cT_(T) x) NE { s.erase(find_<use_bf>(x), s.end()); }
+  CEXP void push_nocheck(cT_(T) x) NE { s.push_back(x); }
+  template <bool use_bf = false>
+  CEXP void push(cT_(T) x) NE { pop_greater<use_bf>(x), s.push_back(x); }
+  template <bool use_bf = false>
+  CEXP void insert(cT_(T) x) NE {
+    if (auto it = find_<use_bf>(x); it == s.end()) s.push_back(x);
+    else *it = x;
+  }
+  CEXP T CR top() CNE { return s.back(); }
+  CEXP u32 size() CNE { return (u32)s.size(); }
+};
+
+}  // namespace tifa_libs::ds
+
+#endif

src/code/opt/hoverline.hpp

@@ -0,0 +1,24 @@
+#ifndef TIFALIBS_OPT_HOVERLINE
+#define TIFALIBS_OPT_HOVERLINE
+
+#include "../util/util.hpp"
+
+namespace tifa_libs::opt {
+
+// @return {l, r} s.t. $\forall x\in[l_i,r_i],~a_x\geq a_i$, $l_i$ leftmost, $r_i$ rightmost
+template <class T, class C = std::less<T>>
+CEXP ptt<vecu> hoverline(vec<T> CR a, C&& comp = C{}) NE {
+  if (a.empty()) return {{}, {}};
+  vecu l(a.size());
+  std::iota(l.begin(), l.end(), 0_u32);
+  auto r = l;
+  flt_ (u32, i, 0, (u32)a.size())
+    while (l[i] && !comp(a[l[i] - 1], a[i])) l[i] = l[l[i] - 1];
+  for (u32 i = (u32)a.size() - 2; ~i; --i)
+    while ((i32)r[i] < (i32)a.size() - 1 && !comp(a[r[i] + 1], a[i])) r[i] = r[r[i] + 1];
+  return {l, r};
+}
+
+}  // namespace tifa_libs::opt
+
+#endif

src/data/bzoj/1660/1.in

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src/data/bzoj/1660/1.out

@@ -0,0 +1 @@
+2571