golf (#92)

* golf

* [auto-verifier] verify commit a77a224

* add asserts for par cent

---------

Co-authored-by: GitHub <[email protected]>

Author: lrvideckis

.verify-helper/timestamps.remote.json

@@ -66,7 +66,7 @@
 "tests/library_checker_aizu_tests/graphs/strongly_connected_components_aizu.test.cpp": "2024-10-19 22:41:15 -0700",
 "tests/library_checker_aizu_tests/graphs/strongly_connected_components_lib_checker.test.cpp": "2024-10-19 22:41:15 -0700",
 "tests/library_checker_aizu_tests/graphs/two_edge_components.test.cpp": "2024-10-19 01:05:18 -0700",
-"tests/library_checker_aizu_tests/handmade_tests/count_paths_forest.test.cpp": "2024-10-29 23:57:39 -0700",
+"tests/library_checker_aizu_tests/handmade_tests/count_paths_forest.test.cpp": "2024-11-07 09:34:29 -0600",
 "tests/library_checker_aizu_tests/handmade_tests/dsu_size.test.cpp": "2024-10-19 22:41:15 -0700",
 "tests/library_checker_aizu_tests/handmade_tests/edge_cd_small_trees.test.cpp": "2024-10-19 01:05:18 -0700",
 "tests/library_checker_aizu_tests/handmade_tests/fib_matrix_expo.test.cpp": "2024-10-19 22:41:15 -0700",
@@ -132,9 +132,9 @@
 "tests/library_checker_aizu_tests/strings/suffix_array.test.cpp": "2024-10-19 22:41:15 -0700",
 "tests/library_checker_aizu_tests/strings/trie.test.cpp": "2024-10-19 01:05:18 -0700",
 "tests/library_checker_aizu_tests/strings/wildcard_pattern_matching.test.cpp": "2024-10-19 01:05:18 -0700",
-"tests/library_checker_aizu_tests/trees/cd_jump_on_tree.test.cpp": "2024-10-29 23:57:39 -0700",
-"tests/library_checker_aizu_tests/trees/cd_lca.test.cpp": "2024-10-29 23:57:39 -0700",
-"tests/library_checker_aizu_tests/trees/count_paths_per_length.test.cpp": "2024-10-29 23:57:39 -0700",
+"tests/library_checker_aizu_tests/trees/cd_jump_on_tree.test.cpp": "2024-11-07 09:34:29 -0600",
+"tests/library_checker_aizu_tests/trees/cd_lca.test.cpp": "2024-11-07 09:34:29 -0600",
+"tests/library_checker_aizu_tests/trees/count_paths_per_length.test.cpp": "2024-11-07 09:34:29 -0600",
 "tests/library_checker_aizu_tests/trees/edge_cd_contour_range_query.test.cpp": "2024-10-19 22:41:15 -0700",
 "tests/library_checker_aizu_tests/trees/edge_cd_contour_range_update.test.cpp": "2024-10-19 22:41:15 -0700",
 "tests/library_checker_aizu_tests/trees/edge_cd_count_paths_per_length.test.cpp": "2024-10-19 01:05:18 -0700",

library/trees/centroid_decomp.hpp

@@ -9,21 +9,21 @@
 template<class F> struct centroid {
   vector<vi> adj;
   F f;
-  vi sub_sz;
+  vi siz;
   centroid(const vector<vi>& a_adj, F a_f):
-    adj(a_adj), f(a_f), sub_sz(sz(adj), -1) {
-    rep(i, 0, sz(adj)) if (sub_sz[i] == -1) dfs(i, -1);
+    adj(a_adj), f(a_f), siz(sz(adj), -1) {
+    rep(i, 0, sz(adj)) if (siz[i] == -1) dfs(i, -1);
   }
   void calc_sz(int v, int p) {
-    sub_sz[v] = 1;
+    siz[v] = 1;
     for (int u : adj[v])
-      if (u != p) calc_sz(u, v), sub_sz[v] += sub_sz[u];
+      if (u != p) calc_sz(u, v), siz[v] += siz[u];
   }
   void dfs(int v, int p) {
     calc_sz(v, -1);
-    for (int w = -1, sz_root = sub_sz[v];;) {
+    for (int w = -1, sz_root = siz[v];;) {
       auto big_ch = find_if(all(adj[v]), [&](int u) {
-        return u != w && 2 * sub_sz[u] > sz_root;
+        return u != w && 2 * siz[u] > sz_root;
       });
       if (big_ch == end(adj[v])) break;
       w = v, v = *big_ch;

tests/library_checker_aizu_tests/cd_asserts.hpp

@@ -1,28 +1,26 @@
 #pragma once
 #include "../../library/trees/centroid_decomp.hpp"
 void cd_asserts(const vector<vector<int>>& adj) {
-  vector<bool> seen_cent(sz(adj));
+  vector<int> decomp_size(sz(adj), -1);
   centroid(adj,
     [&](const vector<vector<int>>& cd_adj, int cent,
-      int) -> void {
-      assert(!seen_cent[cent]);
-      seen_cent[cent] = 1;
+      int par_cent) -> void {
+      assert(decomp_size[cent] == -1);
       auto dfs = [&](auto&& self, int u, int p) -> int {
         int sub_size = 1;
         for (int v : cd_adj[u])
           if (v != p) sub_size += self(self, v, u);
         return sub_size;
       };
-      int sz_decomp = dfs(dfs, cent, -1);
-      int sum = 1;
+      decomp_size[cent] = dfs(dfs, cent, -1);
+      if (par_cent != -1)
+        assert(1 <= decomp_size[cent] &&
+          2 * decomp_size[cent] <= decomp_size[par_cent]);
       for (int u : cd_adj[cent]) {
         int sz_subtree = dfs(dfs, u, cent);
-        sum += sz_subtree;
-        assert(
-          1 <= sz_subtree && 2 * sz_subtree <= sz_decomp);
+        assert(1 <= sz_subtree &&
+          2 * sz_subtree <= decomp_size[cent]);
       }
-      assert(sum == sz_decomp);
     });
-  assert(find(begin(seen_cent), end(seen_cent), 0) ==
-    end(seen_cent));
+  rep(i, 0, sz(adj)) assert(decomp_size[i] >= 1);
 }