seg tree add vector constructor (#177)

* first draft

* [auto-verifier] verify commit 2a37bed

---------

Co-authored-by: GitHub <noreply@github.com>

Author: lrvideckis

.verify-helper/timestamps.remote.json

@@ -44,8 +44,8 @@
 "tests/library_checker_aizu_tests/data_structures/rmq_sparse_table.test.cpp": "2026-01-18 11:15:41 +0000",
 "tests/library_checker_aizu_tests/data_structures/rmq_sparse_table_inc.test.cpp": "2026-01-18 11:15:41 +0000",
 "tests/library_checker_aizu_tests/data_structures/simple_tree.test.cpp": "2026-01-18 11:15:41 +0000",
-"tests/library_checker_aizu_tests/data_structures/simple_tree_inc.test.cpp": "2026-01-24 12:58:11 -0700",
-"tests/library_checker_aizu_tests/data_structures/simple_tree_inc_line.test.cpp": "2026-01-24 12:58:11 -0700",
+"tests/library_checker_aizu_tests/data_structures/simple_tree_inc.test.cpp": "2026-01-28 20:57:42 -0700",
+"tests/library_checker_aizu_tests/data_structures/simple_tree_inc_line.test.cpp": "2026-01-28 20:57:42 -0700",
 "tests/library_checker_aizu_tests/data_structures/simple_tree_line.test.cpp": "2026-01-18 11:15:41 +0000",
 "tests/library_checker_aizu_tests/flow/dinic_aizu.test.cpp": "2024-11-17 14:04:03 -0600",
 "tests/library_checker_aizu_tests/flow/hungarian.test.cpp": "2024-11-17 14:04:03 -0600",

library/data_structures_[l,r]/seg_tree.hpp

@@ -20,6 +20,7 @@ template<class T, class F> struct tree {
   vector<T> s;
   tree(int n, T unit, F op):
     n(n), op(op), s(2 * n, unit) {}
+#include "seg_tree_uncommon/init.hpp"
   void update(int i, T val) {
     for (s[i += n] = val; i /= 2;)
       s[i] = op(s[2 * i], s[2 * i + 1]);

library/data_structures_[l,r]/seg_tree_uncommon/init.hpp

@@ -0,0 +1,7 @@
+#pragma once
+tree(const vector<T>& a, F op):
+  n(sz(a)), op(op), s(2 * n) {
+  rep(i, 0, n) s[i + n] = a[i];
+  for (int i = n - 1; i >= 1; i--)
+    s[i] = op(s[2 * i], s[2 * i + 1]);
+}