lru-cache

Author: logerrors

src/lru-cache/bench.cpp

@@ -0,0 +1,19 @@
+#include "solution.hpp"
+
+#include <benchmark/benchmark.h>
+
+
+static void BM_LRU_Cache(benchmark::State& state) {
+    for (auto _ : state) {
+       auto s = std::make_shared<LRUCache>(2);
+       s->put(2, 1);
+       s->put(1, 1);
+       s->put(2, 3);
+       s->put(4, 1);
+       s->get(1);
+       s->get(2);
+    }
+}
+
+BENCHMARK(BM_LRU_Cache);
+BENCHMARK_MAIN();

src/lru-cache/solution.hpp

@@ -0,0 +1,60 @@
+#include <leetcode.hpp>
+#include <unordered_map>
+#include <list>
+
+using namespace leetcode;
+
+class LRUCache
+{
+public:
+    using kv = std::pair<int, int>;
+    using list_iter = std::list<kv>::iterator;
+
+    LRUCache(int capacity)
+    {
+        this->capacity_ = capacity;
+    }
+
+    int get(int key)
+    {
+        auto it = cache_item_map_.find(key);
+        if (it == cache_item_map_.end())
+        {
+            return -1;
+        }
+        else
+        {
+            cache_item_list_.splice(cache_item_list_.begin(), cache_item_list_, it->second);
+            return it->second->second;
+        }
+    }
+
+    void put(int key, int value)
+    {
+        auto it = cache_item_map_.find(key);
+        if (it == cache_item_map_.end())
+        {
+            cache_item_list_.push_front({key, value});
+            cache_item_map_[key] = cache_item_list_.begin();
+
+            if (cache_item_map_.size() > capacity_)
+            {
+                auto last = cache_item_list_.end();
+                --last;
+                cache_item_map_.erase(last->first);
+                cache_item_list_.pop_back();
+            }
+
+        }
+        else
+        {
+            it->second->second = value;
+            cache_item_list_.splice(cache_item_list_.begin(), cache_item_list_, it->second);
+        }
+    }
+
+private:
+    std::list<kv> cache_item_list_;
+    std::unordered_map<int, list_iter> cache_item_map_;
+    int capacity_;
+};

src/lru-cache/test.cpp

@@ -0,0 +1,32 @@
+#include "solution.hpp"
+#include <memory>
+
+#define CATCH_CONFIG_MAIN
+#include <catch2/catch.hpp>
+
+TEST_CASE(__FILE__){
+    SECTION("example1"){
+       auto s = std::make_shared<LRUCache>(2);
+       s->put(1, 1);
+       s->put(2, 2);
+       REQUIRE(s->get(1) == 1);
+       s->put(3, 3);
+       REQUIRE(s->get(2) == -1);
+       s->put(4, 4);
+       REQUIRE(s->get(1) == -1);
+       REQUIRE(s->get(3) == 3);
+       REQUIRE(s->get(4) == 4);
+    }
+
+    SECTION("example2"){
+       auto s = std::make_shared<LRUCache>(2);
+       s->put(2, 1);
+       s->put(1, 1);
+       s->put(2, 3);
+       s->put(4, 1);
+       REQUIRE(s->get(1) == -1);
+       REQUIRE(s->get(2) == 3);
+    }
+
+
+}

xmake.lua

@@ -35,6 +35,7 @@ define_target("reverse-linked-list")
 define_target("binary-tree-maximum-path-sum")
 define_target("lowest-common-ancestor-of-a-binary-tree")
 define_target("delete-node-in-a-bst")
+define_target("lru-cache")
 
 task("problem")