Google's B-tree挺快
#if 0 #include "set.h" // github.com/Kronuz/cpp-btree using namespace btree; #else #include <set> // en.cppreference.com/w/cpp/container/multiset #endif #include <iostream> using namespace std; typedef multiset<int> S; typedef S::const_iterator I; int main() { S s; for (int i = 0; i < 1000000; i++) s.insert(i), s.insert(i + 10); cout << s.size() << endl; // g++ -x c++ /dev/null -dM -E // g++ -std=c++17 t.cpp #if __cplusplus >= 201703 const auto [a, b] = s.equal_range(12345); #else pair<I,I> two = s.equal_range(12345); I a = two.first, b = two.second; #endif for (auto p = a; p != b; p++) cout << *p << ' '; cout << endl; return 0; }
// 我的电脑上都-Ofast, 分别是1秒和0.35秒。btree得-std=c+++17, std不必须。
Code... is based on Google's B-tree implementation. C++ B-tree is a template library that implements ordered in-memory containers based on a B-tree data structure. Similar to the STL std::map, std::set, std::multimap, and std::multiset templates, this library provides btree::map, btree::set, btree::multimap and btree::multiset... C++ B-tree containers have a few advantages compared with the standard containers, which are typically implemented using Red-Black trees.
B-tree - Detailed Pedia. The B-tree generalizes the binary search tree, allowing for nodes with more than two children. Unlike other self-balancing binary search trees, the B-tree is well suited for storage systems that read and write relatively large blocks of data, such as databases and file systems.
btree.h 3000多行。如果我被要求面试时写红黑树，我就拿出上面的例子，说：“我给你写个更高档的”——反正都写不出来，死得好看点。:-)
btree.h里有这么一段：
* btree_bench --benchmarks=. 2>&1 | ./benchmarks.awk * * Run on pmattis-warp.nyc (4 X 2200 MHz CPUs); 2010/03/04-15:23:06 * Benchmark STL(ns) B-Tree(ns) @ <size> * -------------------------------------------------------- * BM_set_int32_insert 1516 608 +59.89% <256> [40.0, 5.2] * BM_set_int32_lookup 1160 414 +64.31% <256> [40.0, 5.2] * BM_set_int32_fulllookup 960 410 +57.29% <256> [40.0, 4.4] * BM_set_int32_delete 1741 528 +69.67% <256> [40.0, 5.2] * BM_set_int32_queueaddrem 3078 1046 +66.02% <256> [40.0, 5.5] * BM_set_int32_mixedaddrem 3600 1384 +61.56% <256> [40.0, 5.3] * BM_set_int32_fifo 227 113 +50.22% <256> [40.0, 4.4] * BM_set_int32_fwditer 158 26 +83.54% <256> [40.0, 5.2] * BM_map_int32_insert 1551 636 +58.99% <256> [48.0, 10.5] * BM_map_int32_lookup 1200 508 +57.67% <256> [48.0, 10.5] * BM_map_int32_fulllookup 989 487 +50.76% <256> [48.0, 8.8] * BM_map_int32_delete 1794 628 +64.99% <256> [48.0, 10.5] * BM_map_int32_queueaddrem 3189 1266 +60.30% <256> [48.0, 11.6] * BM_map_int32_mixedaddrem 3822 1623 +57.54% <256> [48.0, 10.9] * BM_map_int32_fifo 151 134 +11.26% <256> [48.0, 8.8] * BM_map_int32_fwditer 161 32 +80.12% <256> [48.0, 10.5] * BM_set_int64_insert 1546 636 +58.86% <256> [40.0, 10.5] * BM_set_int64_lookup 1200 512 +57.33% <256> [40.0, 10.5] * BM_set_int64_fulllookup 971 487 +49.85% <256> [40.0, 8.8] * BM_set_int64_delete 1745 616 +64.70% <256> [40.0, 10.5] * BM_set_int64_queueaddrem 3163 1195 +62.22% <256> [40.0, 11.6] * BM_set_int64_mixedaddrem 3760 1564 +58.40% <256> [40.0, 10.9] * BM_set_int64_fifo 146 103 +29.45% <256> [40.0, 8.8] * BM_set_int64_fwditer 162 31 +80.86% <256> [40.0, 10.5] * BM_map_int64_insert 1551 720 +53.58% <256> [48.0, 20.7] * BM_map_int64_lookup 1214 612 +49.59% <256> [48.0, 20.7] * BM_map_int64_fulllookup 994 592 +40.44% <256> [48.0, 17.2] * BM_map_int64_delete 1778 764 +57.03% <256> [48.0, 20.7] * BM_map_int64_queueaddrem 3189 1547 +51.49% <256> [48.0, 20.9] * BM_map_int64_mixedaddrem 3779 1887 +50.07% <256> [48.0, 21.6] * BM_map_int64_fifo 147 145 +1.36% <256> [48.0, 17.2] * BM_map_int64_fwditer 162 41 +74.69% <256> [48.0, 20.7] * BM_set_string_insert 1989 1966 +1.16% <256> [64.0, 44.5] * BM_set_string_lookup 1709 1600 +6.38% <256> [64.0, 44.5] * BM_set_string_fulllookup 1573 1529 +2.80% <256> [64.0, 35.4] * BM_set_string_delete 2520 1920 +23.81% <256> [64.0, 44.5] * BM_set_string_queueaddrem 4706 4309 +8.44% <256> [64.0, 48.3] * BM_set_string_mixedaddrem 5080 4654 +8.39% <256> [64.0, 46.7] * BM_set_string_fifo 318 512 -61.01% <256> [64.0, 35.4] * BM_set_string_fwditer 182 93 +48.90% <256> [64.0, 44.5] * BM_map_string_insert 2600 2227 +14.35% <256> [72.0, 55.8] * BM_map_string_lookup 2068 1730 +16.34% <256> [72.0, 55.8] * BM_map_string_fulllookup 1859 1618 +12.96% <256> [72.0, 44.0] * BM_map_string_delete 3168 2080 +34.34% <256> [72.0, 55.8] * BM_map_string_queueaddrem 5840 4701 +19.50% <256> [72.0, 59.4] * BM_map_string_mixedaddrem 6400 5200 +18.75% <256> [72.0, 57.8] * BM_map_string_fifo 398 596 -49.75% <256> [72.0, 44.0] * BM_map_string_fwditer 243 113 +53.50% <256> [72.0, 55.8]
