From 31c3f9c0c1ae0f4a834f2b28f7e9112e990a2eb5 Mon Sep 17 00:00:00 2001 From: Cool <747682928@qq.com> Date: Tue, 27 Aug 2024 23:59:03 +0800 Subject: [PATCH] 2024/8/27 LeetCode Hot100 LinkedList --- .../com/cool/hot100/linkedlist/LRUCache.java | 162 ++++++++++++++++++ .../com/cool/hot100/linkedlist/Num142.java | 5 - .../com/cool/hot100/linkedlist/Num19.java | 13 +- .../com/cool/hot100/linkedlist/Num23.java | 1 - .../com/cool/hot100/linkedlist/Num25.java | 2 +- 5 files changed, 173 insertions(+), 10 deletions(-) create mode 100644 src/main/java/com/cool/hot100/linkedlist/LRUCache.java diff --git a/src/main/java/com/cool/hot100/linkedlist/LRUCache.java b/src/main/java/com/cool/hot100/linkedlist/LRUCache.java new file mode 100644 index 0000000..f039933 --- /dev/null +++ b/src/main/java/com/cool/hot100/linkedlist/LRUCache.java @@ -0,0 +1,162 @@ +package com.cool.hot100.linkedlist; +// +import org.junit.Test; + +import java.util.HashMap; +import java.util.Map; +// +///** +// * Created with IntelliJ IDEA. +// * +// * @Author: Cool +// * @Date: 2024/08/27/20:00 +// * @Description:LeetCode Hot100 LinkedList最后一题 +// * DayNumber 1 +// * Hard 2 +// * Level 7 +// */ +//public class LRUCache { +// private final int capacity; +// +// private Map map = new HashMap<>(); +// private int size = 0; +// private LRUNode sentry; +// private LRUNode curNode; +// +// public LRUCache(int capacity) { +// this.capacity = capacity; +// } +// +// public int get(int key) { +// LRUNode returnVal = map.getOrDefault(key, null); +// return returnVal == null ? -1 : returnVal.val; +// } +// +// public void put(int key, int value) { +// if (size < capacity) { +//// LRUNode lruNode = new LRUNode(value); +//// curNode.next=lruNode; +//// curNode=curNode.next; +// putList(key, value); +// if (size == 0) sentry = curNode; +//// map.put(key, lruNode); +// size++; +// } else { +// if (exist(key)) { +// putList(key, value); +// } else { +// putList(key, value); +// int val = sentry.val; +// remove(val); +// sentry = sentry.next; +// } +// +// } +// } +// +// private void remove(int key) { +// map.remove(key); +// } +// +// private boolean exist(int key) { +// return map.containsKey(key); +// } +// +// public void putList(int key, int value) { +// LRUNode node = new LRUNode(value); +// if(curNode==null){ +// curNode=node; +// }else{ +// curNode.next = node; +// curNode = curNode.next; +// } +// map.put(key, node); +// } +// +//} +// +//class LRUNode { +// int val; +// LRUNode next; +// LRUNode pre; +// +// +// LRUNode() { +// } +// +// LRUNode(int val) { +// this.val = val; +// } +// +// LRUNode(int val, LRUNode pre, LRUNode next) { +// this.val = val; +// this.pre = pre; +// this.next = next; +// } +//} +class LRUCache { + private static class Node { + int key, value; + Node prev, next; + + Node(int k, int v) { + key = k; + value = v; + } + } + + private final int capacity; + private final Node dummy = new Node(0, 0); // 哨兵节点 + private final Map keyToNode = new HashMap<>(); + + public LRUCache(int capacity) { + this.capacity = capacity; + dummy.prev = dummy; + dummy.next = dummy; + } + + public int get(int key) { + Node node = getNode(key); + return node != null ? node.value : -1; + } + + public void put(int key, int value) { + Node node = getNode(key); + if (node != null) { // 有这本书 + node.value = value; // 更新 value + return; + } + node = new Node(key, value); // 新书 + keyToNode.put(key, node); + pushFront(node); // 放在最上面 + if (keyToNode.size() > capacity) { // 书太多了 + Node backNode = dummy.prev; + keyToNode.remove(backNode.key); + remove(backNode); // 去掉最后一本书 + } + } + + private Node getNode(int key) { + if (!keyToNode.containsKey(key)) { // 没有这本书 + return null; + } + Node node = keyToNode.get(key); // 有这本书 + remove(node); // 把这本书抽出来 + pushFront(node); // 放在最上面 + return node; + } + + // 删除一个节点（抽出一本书） + private void remove(Node x) { + x.prev.next = x.next; + x.next.prev = x.prev; + } + + // 在链表头添加一个节点（把一本书放在最上面） + private void pushFront(Node x) { + x.prev = dummy; + x.next = dummy.next; + x.prev.next = x; + x.next.prev = x; + } +} diff --git a/src/main/java/com/cool/hot100/linkedlist/Num142.java b/src/main/java/com/cool/hot100/linkedlist/Num142.java index 3821966..ac6c860 100644 --- a/src/main/java/com/cool/hot100/linkedlist/Num142.java +++ b/src/main/java/com/cool/hot100/linkedlist/Num142.java @@ -2,11 +2,6 @@ package com.cool.hot100.linkedlist; import org.junit.Test; -import java.util.ArrayList; -import java.util.HashMap; -import java.util.List; -import java.util.Map; - public class Num142 { diff --git a/src/main/java/com/cool/hot100/linkedlist/Num19.java b/src/main/java/com/cool/hot100/linkedlist/Num19.java index 970fff6..8994774 100644 --- a/src/main/java/com/cool/hot100/linkedlist/Num19.java +++ b/src/main/java/com/cool/hot100/linkedlist/Num19.java @@ -2,9 +2,6 @@ package com.cool.hot100.linkedlist; import org.junit.Test; -import java.util.ArrayList; -import java.util.List; - public class Num19 { @@ -60,4 +57,14 @@ public class Num19 { ListNode node1 = new ListNode(2, node); removeNthFromEnd(node1, 1); } + @Test + public void test1(){ + LRUCache cache=new LRUCache(2); + cache.put(1,1); + cache.put(2,2); + cache.get(1); + cache.put(3,3); + System.out.println(cache.get(2)); + cache.put(4,4); + } } diff --git a/src/main/java/com/cool/hot100/linkedlist/Num23.java b/src/main/java/com/cool/hot100/linkedlist/Num23.java index 9de180f..ad1ca16 100644 --- a/src/main/java/com/cool/hot100/linkedlist/Num23.java +++ b/src/main/java/com/cool/hot100/linkedlist/Num23.java @@ -1,6 +1,5 @@ package com.cool.hot100.linkedlist; -import java.util.ArrayList; import java.util.Arrays; import java.util.List; import java.util.stream.Collectors; diff --git a/src/main/java/com/cool/hot100/linkedlist/Num25.java b/src/main/java/com/cool/hot100/linkedlist/Num25.java index c62c9e8..00bc758 100644 --- a/src/main/java/com/cool/hot100/linkedlist/Num25.java +++ b/src/main/java/com/cool/hot100/linkedlist/Num25.java @@ -37,7 +37,7 @@ public class Num25 { } - private ListNode[] reverse(ListNode head,ListNode next) { + private ListNode[] reverse(ListNode head, ListNode next) { ListNode node = head; ListNode pre = null; ListNode nxt=next.next;