perf: simplify

src/code/ds/rus4_st.hpp

@@ -5,14 +5,14 @@
 
 namespace tifa_libs::ds {
 
-template <class T, auto op, T (*e)()>
-requires std::same_as<std::remove_cvref_t<decltype(op(T(), T()))>, T>
+template <class T, auto op>
 class rus4_st {
   u32 sz, B;
-  st_array<T, op, e> st;
-  vec<st_array<T, op, e>> d;
+  st_array<T, op> st;
+  vec<st_array<T, op>> d;
 
  public:
+  CEXPE rus4_st(spn<T> a) : rus4_st(a, (u32)std::bit_width(a.size())) {}
   CEXP rus4_st(spn<T> a, u32 block_size) { reset(a, block_size); }
 
   CEXP void reset(spn<T> a, u32 block_size) {
@@ -23,13 +23,17 @@ class rus4_st {
   }
   CEXP u32 CR block_size() const { return B; }
   CEXP u32 CR size() const { return sz; }
-  //! 0-indexed
-  CEXP T query(u32 l = 0) const { return query(l, sz); }
-  //! 0-indexed, [l, r]
+  CEXP T query(u32 l = 0) const { return query(l, size()); }
+  //! 0-indexed, [l, r)
   CEXP T query(u32 l, u32 r) const {
-    if (r <= l) return e();
+    assert(l < r && r <= size());
     if (u32 L = l / B, R = r / B; L == R) return d[L].query(l % B, r % B);
-    else return op(op(d[L].query(l % B), st.query(L + 1, R)), d[R].query(0, r % B));
+    else {
+      T ret = d[L].query(l % B);
+      if (L + 1 != R) ret = op(ret, st.query(L + 1, R));
+      if (r % B) ret = op(ret, d[R].query(0, r % B));
+      return ret;
+    }
   }
 };
 

src/code/ds/segtree.hpp

@@ -14,8 +14,8 @@ requires requires(T val, T new_val, F tag, F new_tag) {
   { id() } -> std::same_as<F>;
 }
 class segtree {
-  const T E = e();
-  const F ID = id();
+  static inline const T E = e();
+  static inline const F ID = id();
   u32 sz, lbn, n;
   vec<T> val;
   vec<F> tag;
@@ -24,7 +24,7 @@ class segtree {
  public:
   template <class V>
   CEXPE segtree(V &&a) { reset(std::forward<V>(a)); }
-  CEXPE segtree(u32 n = 0) : segtree(vec<T>(n, e())) {}
+  CEXPE segtree(u32 n = 0) : segtree(vec<T>(n, E)) {}
 
   template <class V>
   CEXP void reset(V &&a) {

src/code/ds/st_array.hpp

@@ -5,7 +5,7 @@
 
 namespace tifa_libs::ds {
 
-template <class T, auto op, T (*e)()>
+template <class T, auto op>
 requires std::same_as<std::remove_cvref_t<decltype(op(T(), T()))>, T>
 class st_array {
   vvec<T> st;
@@ -16,7 +16,7 @@ class st_array {
 
   CEXP void reset(spn<T> a) {
     const u32 n = (u32)a.size(), lbn = (u32)std::bit_width(n);
-    st = vvec<T>(lbn, vec<T>(n, e())), std::ranges::copy(a, st[0].begin());
+    st = vvec<T>(lbn, vec<T>(n)), std::ranges::copy(a, st[0].begin());
     flt_ (u32, j, 1, lbn)
       flt_ (u32, i, 0, n) st[j][i] = op(st[j - 1][i], st[j - 1][(u32)max(0, i32(i - (1 << (j - 1))))]);
   }
@@ -27,16 +27,17 @@ class st_array {
     }
     const u32 n = size() + 1, lbn = (u32)std::bit_width(n);
     if (st[0].push_back(x); std::has_single_bit(n)) {
-      st.emplace_back(n - 1, e());
+      st.emplace_back(n - 1);
       flt_ (u32, i, 0, n - 1) st.back()[i] = op(st[lbn - 2][i], st[lbn - 2][(u32)max(0, i32(i - (1 << (lbn - 2))))]);
     }
     flt_ (u32, j, 1, lbn) st[j].push_back(op(st[j - 1].back(), st[j - 1][n - 1 - (1 << (j - 1))]));
   }
   CEXP u32 height() const { return (u32)st.size(); }
-  CEXP u32 size() const { return (u32)st[0].size(); }
+  CEXP u32 size() const { return height() ? (u32)st[0].size() : 0; }
   CEXP T query(u32 l = 0) const { return query(l, size()); }
+  //! 0-indexed, [l, r)
   CEXP T query(u32 l, u32 r) const {
-    if (r <= l) return e();
+    assert(l < r && r <= size());
     const u32 k = (u32)(std::bit_width(r - l) - 1);
     return op(st[k][l + (1 << k) - 1], st[k][r - 1]);
   }

src/test_cpverifier/library-checker-datastructure/staticrmq.rus4_st.test.cpp

@@ -3,7 +3,6 @@
 #include "../../code/ds/rus4_st.hpp"
 
 i32 f(i32 x, i32 y) { return tifa_libs::min(x, y); }
-i32 e() { return std::numeric_limits<i32>::max(); }
 
 int main() {
   std::cin.tie(nullptr)->std::ios::sync_with_stdio(false);
@@ -12,13 +11,13 @@ int main() {
   veci a(n);
   flt_ (u32, i, 0, n) std::cin >> a[i];
   if (n < 16) {
-    tifa_libs::ds::st_array<i32, f, e> st(a);
+    tifa_libs::ds::st_array<i32, f> st(a);
     for (u32 i = 1, u, v; i <= q; ++i) {
       std::cin >> u >> v;
       std::cout << st.query(u, v) << '\n';
     }
   } else {
-    tifa_libs::ds::rus4_st<i32, f, e> st(a, (u32)std::bit_width(n));
+    tifa_libs::ds::rus4_st<i32, f> st(a);
     for (u32 i = 1, u, v; i <= q; ++i) {
       std::cin >> u >> v;
       std::cout << st.query(u, v) << '\n';

src/test_cpverifier/library-checker-datastructure/staticrmq.st_array.test.cpp

@@ -3,15 +3,14 @@
 #include "../../code/ds/st_array.hpp"
 
 i32 f(i32 x, i32 y) { return tifa_libs::min(x, y); }
-i32 e() { return std::numeric_limits<i32>::max(); }
 
 int main() {
   std::cin.tie(nullptr)->std::ios::sync_with_stdio(false);
   u32 n, q;
   std::cin >> n >> q;
   veci a(n);
   flt_ (u32, i, 0, n) std::cin >> a[i];
-  tifa_libs::ds::st_array<i32, f, e> st(a);
+  tifa_libs::ds::st_array<i32, f> st(a);
   for (u32 i = 1, u, v; i <= q; ++i) {
     std::cin >> u >> v;
     std::cout << st.query(u, v) << '\n';

src/test_cpverifier/unit-test/ds/st_array.bzoj1012.test.cpp

@@ -6,15 +6,14 @@
 #include "../base.hpp"
 
 i64 f(i64 x, i64 y) { return tifa_libs::max(x, y); }
-i64 e() { return 0; }
 
 void test(strn CR data) {
   auto [fn_in, fn_ans] = tifa_libs::unittest::get_fname_in_ans("bzoj", "1012", data);
   std::ifstream fin(fn_in), fans(fn_ans);
 
   u32 m, d;
   fin >> m >> d;
-  tifa_libs::ds::st_array<i64, f, e> st;
+  tifa_libs::ds::st_array<i64, f> st;
   char op;
   i64 t = 0, u;
   for (u32 i = 1; i <= m; ++i) {