{"id":406,"date":"2025-09-24T17:59:31","date_gmt":"2025-09-24T09:59:31","guid":{"rendered":"https:\/\/heyingnian.com\/?p=406"},"modified":"2025-09-24T18:00:14","modified_gmt":"2025-09-24T10:00:14","slug":"leetcode-146","status":"publish","type":"post","link":"https:\/\/heyingnian.com\/index.php\/2025\/09\/24\/leetcode-146\/","title":{"rendered":"LRU \u7f13\u5b58"},"content":{"rendered":"\n<h1 class=\"wp-block-heading\">\ud83d\udd17 LRU \u7f13\u5b58<\/h1>\n\n\n\n<p>\u9898\u76ee\u6765\u6e90\uff1a<a target=\"_blank\" rel=\"noreferrer noopener\"><a href=\"https:\/\/leetcode.cn\/problems\/lru-cache\/description\/?envType=study-plan-v2&amp;envId=top-100-liked\" target=\"_blank\" rel=\"noopener\">146. LRU \u7f13\u5b58 &#8211; \u529b\u6263\uff08LeetCode\uff09<\/a><\/a><\/p>\n\n\n\n<p>\ud83d\udccc \u9898\u76ee\u8981\u6c42<\/p>\n\n\n\n<p>\u8bbe\u8ba1\u4e00\u4e2a\u6ee1\u8db3 <strong>LRU\uff08Least Recently Used\uff0c\u6700\u8fd1\u6700\u5c11\u4f7f\u7528\uff09<\/strong> \u7b56\u7565\u7684\u7f13\u5b58\u7ed3\u6784\uff0c\u652f\u6301\u4ee5\u4e0b\u64cd\u4f5c\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>LRUCache(int capacity)<\/code>\uff1a\u4ee5\u6b63\u6574\u6570\u00a0<code>capacity<\/code>\u00a0\u521d\u59cb\u5316\u7f13\u5b58<\/li>\n\n\n\n<li><code>int get(int key)<\/code>\uff1a\u82e5 key \u5b58\u5728\uff0c\u8fd4\u56de\u5bf9\u5e94\u503c\uff0c\u5e76\u5c06\u5176\u6807\u8bb0\u4e3a\u201c\u6700\u8fd1\u4f7f\u7528\u201d\uff1b\u5426\u5219\u8fd4\u56de\u00a0<code>-1<\/code><\/li>\n\n\n\n<li><code>void put(int key, int value)<\/code>\uff1a\n<ul class=\"wp-block-list\">\n<li>\u82e5 key \u5df2\u5b58\u5728\uff0c\u66f4\u65b0\u5176\u503c\u5e76\u6807\u8bb0\u4e3a\u201c\u6700\u8fd1\u4f7f\u7528\u201d<\/li>\n\n\n\n<li>\u82e5 key \u4e0d\u5b58\u5728\uff0c\u63d2\u5165\u65b0\u952e\u503c\u5bf9<\/li>\n\n\n\n<li>\u82e5\u63d2\u5165\u540e\u8d85\u51fa\u5bb9\u91cf\uff0c<strong>\u6dd8\u6c70\u6700\u4e45\u672a\u4f7f\u7528\u7684 key<\/strong><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<p>\u2705 \u6838\u5fc3\u7ea6\u675f\uff1a<code>get<\/code> \u548c <code>put<\/code> \u5fc5\u987b\u4ee5 <strong>O(1) \u5e73\u5747\u65f6\u95f4\u590d\u6742\u5ea6<\/strong> \u8fd0\u884c\u3002<\/p>\n\n\n\n<p>\u2705 \u793a\u4f8b\u8bf4\u660e<\/p>\n\n\n\n<pre class=\"wp-block-preformatted\"><code>\u8f93\u5165\uff1a<br>[\"LRUCache\", \"put\", \"put\", \"get\", \"put\", \"get\", \"put\", \"get\", \"get\", \"get\"]<br>[[2], [1,1], [2,2], [1], [3,3], [2], [4,4], [1], [3], [4]]<br><br>\u8f93\u51fa\uff1a<br>[null, null, null, 1, null, -1, null, -1, 3, 4]<\/code><\/pre>\n\n\n\n<p>\u89e3\u91ca\uff1a\u5bb9\u91cf\u4e3a 2\uff0c\u5f53\u63d2\u5165\u7b2c 3 \u4e2a\u5143\u7d20\u65f6\uff0c\u6dd8\u6c70\u6700\u4e45\u672a\u4f7f\u7528\u7684\uff082\uff09\uff0c\u540e\u7eed\u540c\u7406\u3002<\/p>\n\n\n\n<p>\ud83d\udca1 \u89e3\u6cd5\uff1a\u54c8\u5e0c\u8868 + \u865a\u62df\u5934\u5c3e\u8282\u70b9\u7684\u53cc\u5411\u94fe\u8868<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>class LRUCache {\n    private class Node {\n        int key, value;\n        Node prev, next;\n        Node(int key, int value) {\n            this.key = key;\n            this.value = value;\n        }\n    }\n\n    private int capacity;\n    private Node dummy = new Node(-1, -1);\n    private Map&lt;Integer, Node> map = new HashMap&lt;>();\n\n    public LRUCache(int capacity) {\n        this.capacity = capacity;\n        dummy.next = dummy;\n        dummy.prev = dummy;\n    }\n\n    public int get(int key) {\n        if (!map.containsKey(key)) return -1;\n        Node node = map.get(key);\n        remove(node);\n        addToHead(node);\n        return node.value;\n    }\n\n    public void put(int key, int value) {\n        if (map.containsKey(key)) {\n            Node node = map.get(key);\n            node.value = value;\n            remove(node);\n            addToHead(node);\n        } else {\n            if (map.size() == capacity) {\n                Node tail = dummy.prev;\n                remove(tail);\n                map.remove(tail.key);\n            }\n            Node newNode = new Node(key, value);\n            addToHead(newNode);\n            map.put(key, newNode);\n        }\n    }\n\n    private void remove(Node node) {\n        node.prev.next = node.next;\n        node.next.prev = node.prev;\n    }\n\n    private void addToHead(Node node) {\n        node.next = dummy.next;\n        node.prev = dummy;\n        dummy.next.prev = node;\n        dummy.next = node;\n    }\n}<\/code><\/pre>\n\n\n\n<p>\ud83d\udcca \u590d\u6742\u5ea6\u5206\u6790<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>\u65f6\u95f4\u590d\u6742\u5ea6\uff1aO(1)<\/strong>\n<ul class=\"wp-block-list\">\n<li>\u54c8\u5e0c\u8868\u652f\u6301 O(1) \u67e5\u627e<\/li>\n\n\n\n<li>\u53cc\u5411\u94fe\u8868\u652f\u6301 O(1) \u5220\u9664\u4e0e\u5934\u63d2<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>\u7a7a\u95f4\u590d\u6742\u5ea6\uff1aO(capacity)<\/strong>\n<ul class=\"wp-block-list\">\n<li>\u6700\u591a\u5b58\u50a8\u00a0<code>capacity<\/code>\u00a0\u4e2a\u8282\u70b9<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<p>\ud83e\udde9 \u8bbe\u8ba1\u539f\u7406<\/p>\n\n\n\n<p>LRU \u7684\u6838\u5fc3\u662f <strong>\u5feb\u901f\u5b9a\u4f4d + \u5feb\u901f\u8c03\u6574\u4f7f\u7528\u987a\u5e8f<\/strong>\uff0c\u9700\u540c\u65f6\u6ee1\u8db3\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>\u5feb\u901f\u67e5\u627e<\/strong>\u00a0\u2192 \u4f7f\u7528\u00a0<code>HashMap&lt;Integer, Node><\/code>\uff0ckey \u6620\u5c04\u5230\u94fe\u8868\u8282\u70b9<\/li>\n\n\n\n<li><strong>\u7ef4\u62a4\u4f7f\u7528\u987a\u5e8f<\/strong>\u00a0\u2192 \u4f7f\u7528<strong>\u53cc\u5411\u94fe\u8868<\/strong>\uff1a\n<ul class=\"wp-block-list\">\n<li>\u94fe\u8868\u5934\u90e8\uff1a\u6700\u8fd1\u4f7f\u7528<\/li>\n\n\n\n<li>\u94fe\u8868\u5c3e\u90e8\uff1a\u6700\u4e45\u672a\u4f7f\u7528<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>\u5feb\u901f\u5220\u9664\u5c3e\u8282\u70b9 &amp; \u63d2\u5165\u5934\u8282\u70b9<\/strong>\u00a0\u2192 \u53cc\u5411\u94fe\u8868\u5929\u7136\u652f\u6301 O(1) \u64cd\u4f5c<\/li>\n<\/ol>\n\n\n\n<p>\u4e3a\u7b80\u5316\u8fb9\u754c\u5904\u7406\uff0c\u5f15\u5165<strong>\u865a\u62df\u5934\u8282\u70b9 <code>dummy<\/code><\/strong>\uff0c\u6784\u6210\u73af\u72b6\u7ed3\u6784\uff08<code>dummy.next<\/code> \u4e3a\u771f\u5b9e\u5934\uff0c<code>dummy.prev<\/code> \u4e3a\u771f\u5b9e\u5c3e\uff09\uff0c\u907f\u514d\u7a7a\u6307\u9488\u5224\u65ad\u3002<\/p>\n\n\n\n<p>\u64cd\u4f5c\u903b\u8f91\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>get(key)<\/strong>\uff1a\n<ul class=\"wp-block-list\">\n<li>\u4e0d\u5b58\u5728 \u2192 \u8fd4\u56de -1<\/li>\n\n\n\n<li>\u5b58\u5728 \u2192 \u4ece\u94fe\u8868\u4e2d\u79fb\u9664\u8be5\u8282\u70b9\uff0c\u91cd\u65b0\u63d2\u5165\u5934\u90e8\uff0c\u8fd4\u56de\u503c<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>put(key, value)<\/strong>\uff1a\n<ul class=\"wp-block-list\">\n<li>\u5df2\u5b58\u5728 \u2192 \u66f4\u65b0\u503c\uff0c\u79fb\u81f3\u5934\u90e8<\/li>\n\n\n\n<li>\u4e0d\u5b58\u5728\uff1a\n<ul class=\"wp-block-list\">\n<li>\u82e5\u5df2\u6ee1 \u2192 \u5220\u9664\u5c3e\u8282\u70b9\uff08<code>dummy.prev<\/code>\uff09\uff0c\u4ece map \u4e2d\u79fb\u9664<\/li>\n\n\n\n<li>\u521b\u5efa\u65b0\u8282\u70b9\uff0c\u63d2\u5165\u5934\u90e8\uff0c\u52a0\u5165 map<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>\ud83d\udd17 LRU \u7f13\u5b58 \u9898\u76ee\u6765\u6e90\uff1a146. LRU \u7f13\u5b58 &#8211; \u529b\u6263\uff08LeetCode\uff09 \ud83d\udccc \u9898\u76ee\u8981\u6c42 \u8bbe [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[12,38],"tags":[14,51],"class_list":["post-406","post","type-post","status-publish","format-standard","hentry","category-algorithm","category-linked_list","tag-algorithm","tag-linked_list"],"_links":{"self":[{"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/posts\/406","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/comments?post=406"}],"version-history":[{"count":1,"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/posts\/406\/revisions"}],"predecessor-version":[{"id":407,"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/posts\/406\/revisions\/407"}],"wp:attachment":[{"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/media?parent=406"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/categories?post=406"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/heyingnian.com\/index.php\/wp-json\/wp\/v2\/tags?post=406"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}