diff --git a/include/s0146_lru_cache.hpp b/include/s0146_lru_cache.hpp
new file mode 100644
index 0000000..7a810bd
--- /dev/null
+++ b/include/s0146_lru_cache.hpp
@@ -0,0 +1,50 @@
+#ifndef S0146_LRU_CACHE_HPP
+#define S0146_LRU_CACHE_HPP
+
+#include <cstdlib>
+#include <unordered_map>
+
+class LRUCache {
+ public:
+  /**
+   * @brief Least Recently Used Cache
+   *
+   * 这是一种常用的页面置换算法，选择最近最久未使用的页面予以淘汰
+   *
+   * @param capacity 容量，这是一个正整数
+   */
+  LRUCache(int capacity);
+  /**
+   * @brief 读取数据
+   *
+   * @param key 数据对应的键值
+   * @return 数据的值
+   */
+  int get(int key);
+  /**
+   * @brief 放入对应的数据
+   *
+   * @param key 数据对应的键值
+   * @param value 数据对应的值
+   */
+  void put(int key, int value);
+
+ private:
+  struct CacheNode {
+    int key;
+    int value;
+    CacheNode *next;
+    CacheNode *prev;
+    CacheNode(int key, int value)
+        : key(key), value(value), next(nullptr), prev(nullptr){};
+    CacheNode(int key, int value, CacheNode *next, CacheNode *prev)
+        : key(key), value(value), next(next), prev(prev){};
+  };
+  CacheNode *head;
+  CacheNode *tail;
+  int capacity;
+  std::unordered_map<int, CacheNode *> map;  // 键值是 key，值是该节点的指针
+  void moveToHead(CacheNode *node);          // 将节点移动到头部
+};
+
+#endif
diff --git a/notes/src/SUMMARY.md b/notes/src/SUMMARY.md
index 7450af0..8c47505 100644
--- a/notes/src/SUMMARY.md
+++ b/notes/src/SUMMARY.md
@@ -77,3 +77,4 @@
 - [单调队列](./stack_and_queue.md)
 - [二叉树遍历](./btree_iter.md)
 - [合并两个有序链表](./merge_two_sorted_linked_lists.md)
+- [LRU](./lru_cache.md)
diff --git a/notes/src/lru_cache.md b/notes/src/lru_cache.md
new file mode 100644
index 0000000..161440f
--- /dev/null
+++ b/notes/src/lru_cache.md
@@ -0,0 +1,128 @@
+# LRU
+
+[Leetcode 146. LRU Cache](https://leetcode.cn/problems/lru-cache/description/)
+
+Header:
+
+```cpp
+#ifndef S0146_LRU_CACHE_HPP
+#define S0146_LRU_CACHE_HPP
+
+#include <cstdlib>
+#include <unordered_map>
+
+class LRUCache {
+ public:
+  /**
+   * @brief Least Recently Used Cache
+   *
+   * 这是一种常用的页面置换算法，选择最近最久未使用的页面予以淘汰
+   *
+   * @param capacity 容量，这是一个正整数
+   */
+  LRUCache(int capacity);
+  /**
+   * @brief 读取数据
+   *
+   * @param key 数据对应的键值
+   * @return 数据的值
+   */
+  int get(int key);
+  /**
+   * @brief 放入对应的数据
+   *
+   * @param key 数据对应的键值
+   * @param value 数据对应的值
+   */
+  void put(int key, int value);
+
+ private:
+  struct CacheNode {
+    int key;
+    int value;
+    CacheNode *next;
+    CacheNode *prev;
+    CacheNode(int key, int value)
+        : key(key), value(value), next(nullptr), prev(nullptr){};
+    CacheNode(int key, int value, CacheNode *next, CacheNode *prev)
+        : key(key), value(value), next(next), prev(prev){};
+  };
+  CacheNode *head;
+  CacheNode *tail;
+  int capacity;
+  std::unordered_map<int, CacheNode *> map;  // 键值是 key，值是该节点的指针
+  void moveToHead(CacheNode *node);          // 将节点移动到头部
+};
+
+#endif
+```
+
+Source:
+
+```cpp
+#include "s0146_lru_cache.hpp"
+
+void LRUCache::moveToHead(CacheNode *node) {
+  // 如果是头部节点
+  if (node == head) return;
+  // 如果不是头部节点，但是是尾部节点
+  if (node == tail) tail = node->prev;
+  // 处理该节点的前后两个节点的指针
+  if (node->prev) node->prev->next = node->next;
+  if (node->next) node->next->prev = node->prev;
+  // 将该节点移动到头部
+  node->prev = nullptr;
+  node->next = head;
+  // 处理头部节点
+  head->prev = node;
+  head = node;
+}
+
+LRUCache::LRUCache(int capacity) {
+  this->capacity = capacity;
+  head = nullptr;
+  tail = nullptr;
+  map = std::unordered_map<int, CacheNode *>();
+}
+
+int LRUCache::get(int key) {
+  if (map.size() == 0) return -1;
+  if (map.count(key) == 0) return -1;
+  moveToHead(map[key]);
+  return map[key]->value;
+}
+
+void LRUCache::put(int key, int value) {
+  // 如果 key 已存在，则更新 value ，并将这个节点移动到头部
+  if (map.count(key) == 1) {
+    map[key]->value = value;
+    moveToHead(map[key]);
+    return;
+  }
+  // 否则创建该节点
+  CacheNode *newNode = (CacheNode *)malloc(sizeof(CacheNode));
+  newNode->value = value;
+  newNode->key = key;
+  newNode->next = head;
+  newNode->prev = nullptr;
+  // 处理头部节点
+  if (head) head->prev = newNode;
+  head = newNode;
+  // 处理尾部节点
+  if (map.size() == 0) tail = newNode;
+  // 更新哈希表
+  map[key] = newNode;
+  // 如果容量已满
+  if (map.size() > capacity) {
+    // 更新尾部节点
+    CacheNode *node = tail;
+    if (tail->prev) {
+      tail->prev->next = nullptr;
+      tail = tail->prev;
+    }
+    // 移除该节点
+    map.erase(node->key);
+    free(node);
+  }
+}
+```
diff --git a/src/s0146_lru_cache.cpp b/src/s0146_lru_cache.cpp
new file mode 100644
index 0000000..db2fc2a
--- /dev/null
+++ b/src/s0146_lru_cache.cpp
@@ -0,0 +1,65 @@
+#include "s0146_lru_cache.hpp"
+
+void LRUCache::moveToHead(CacheNode *node) {
+  // 如果是头部节点
+  if (node == head) return;
+  // 如果不是头部节点，但是是尾部节点
+  if (node == tail) tail = node->prev;
+  // 处理该节点的前后两个节点的指针
+  if (node->prev) node->prev->next = node->next;
+  if (node->next) node->next->prev = node->prev;
+  // 将该节点移动到头部
+  node->prev = nullptr;
+  node->next = head;
+  // 处理头部节点
+  head->prev = node;
+  head = node;
+}
+
+LRUCache::LRUCache(int capacity) {
+  this->capacity = capacity;
+  head = nullptr;
+  tail = nullptr;
+  map = std::unordered_map<int, CacheNode *>();
+}
+
+int LRUCache::get(int key) {
+  if (map.size() == 0) return -1;
+  if (map.count(key) == 0) return -1;
+  moveToHead(map[key]);
+  return map[key]->value;
+}
+
+void LRUCache::put(int key, int value) {
+  // 如果 key 已存在，则更新 value ，并将这个节点移动到头部
+  if (map.count(key) == 1) {
+    map[key]->value = value;
+    moveToHead(map[key]);
+    return;
+  }
+  // 否则创建该节点
+  CacheNode *newNode = (CacheNode *)malloc(sizeof(CacheNode));
+  newNode->value = value;
+  newNode->key = key;
+  newNode->next = head;
+  newNode->prev = nullptr;
+  // 处理头部节点
+  if (head) head->prev = newNode;
+  head = newNode;
+  // 处理尾部节点
+  if (map.size() == 0) tail = newNode;
+  // 更新哈希表
+  map[key] = newNode;
+  // 如果容量已满
+  if (map.size() > capacity) {
+    // 更新尾部节点
+    CacheNode *node = tail;
+    if (tail->prev) {
+      tail->prev->next = nullptr;
+      tail = tail->prev;
+    }
+    // 移除该节点
+    map.erase(node->key);
+    free(node);
+  }
+}
diff --git a/tests/s0146_lru_cache.cpp b/tests/s0146_lru_cache.cpp
new file mode 100644
index 0000000..d43813d
--- /dev/null
+++ b/tests/s0146_lru_cache.cpp
@@ -0,0 +1,26 @@
+#include "s0146_lru_cache.hpp"
+
+#include <gtest/gtest.h>
+
+TEST(Problem146, Case1) {
+  LRUCache *lru = new LRUCache(2);
+  lru->put(1, 1);
+  lru->put(2, 2);
+  EXPECT_EQ(lru->get(1), 1);
+  lru->put(3, 3);
+  EXPECT_EQ(lru->get(2), -1);
+  lru->put(4, 4);
+  EXPECT_EQ(lru->get(1), -1);
+  EXPECT_EQ(lru->get(3), 3);
+  EXPECT_EQ(lru->get(4), 4);
+}
+
+TEST(Problem146, Case2) {
+  LRUCache *lru = new LRUCache(2);
+  lru->put(2, 1);
+  lru->put(1, 1);
+  lru->put(2, 3);
+  lru->put(4, 1);
+  EXPECT_EQ(lru->get(1), -1);
+  EXPECT_EQ(lru->get(2), 3);
+}