algorithmzuo
2 years ago
parent
b9a992340e
commit
7189c8d690
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package 第03期.mca_04;
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// 给定一棵二叉树，你需要计算它的直径长度
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// 一棵二叉树的直径长度是任意两个结点路径长度中的最大值
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// 这条路径可能穿过也可能不穿过根结点
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// 测试链接 : https://leetcode.cn/problems/diameter-of-binary-tree/
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public class Code02_DiameterOfBinaryTree {
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// 提交时不要提交这个类
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public static class TreeNode {
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public int val;
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public TreeNode left;
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public TreeNode right;
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public TreeNode(int value) {
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val = value;
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}
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}
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// 提交以下的方法
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public static int diameterOfBinaryTree(TreeNode root) {
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return process(root).maxDistance;
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}
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public static class Info {
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public int maxDistance;
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public int height;
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public Info(int m, int h) {
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maxDistance = m;
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height = h;
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}
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}
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public static Info process(TreeNode x) {
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if (x == null) {
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return new Info(0, 0);
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}
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Info leftInfo = process(x.left);
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Info rightInfo = process(x.right);
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int height = Math.max(leftInfo.height, rightInfo.height) + 1;
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int p1 = Math.max(leftInfo.maxDistance, rightInfo.maxDistance);
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int p2 = leftInfo.height + rightInfo.height;
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int maxDistance = Math.max(p1, p2);
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return new Info(maxDistance, height);
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}
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}
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@ -0,0 +1,122 @@
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package 第03期.mca_04;
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import java.util.HashMap;
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// 本题测试链接 : https://leetcode.cn/problems/lru-cache/
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public class Code08_LRUCache {
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// 提交以下这个类
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public class LRUCache {
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public static class Node {
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public int key;
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public int val;
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public Node last;
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public Node next;
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public Node(int k, int v) {
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key = k;
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val = v;
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}
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}
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public static class DoubleLinkedList {
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private Node head;
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private Node tail;
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public DoubleLinkedList() {
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head = null;
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tail = null;
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}
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public void addNode(Node newNode) {
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if (newNode == null) {
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return;
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}
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if (head == null) {
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head = newNode;
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tail = newNode;
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} else {
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tail.next = newNode;
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newNode.last = tail;
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tail = newNode;
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}
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}
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public void moveNodeToTail(Node node) {
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if (tail == node) {
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return;
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}
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if (head == node) {
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head = node.next;
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head.last = null;
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} else {
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node.last.next = node.next;
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node.next.last = node.last;
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}
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node.last = tail;
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node.next = null;
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this.tail.next = node;
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this.tail = node;
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}
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public Node removeHead() {
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if (head == null) {
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return null;
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}
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Node ans = this.head;
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if (head == tail) {
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head = null;
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tail = null;
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} else {
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head = ans.next;
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ans.next = null;
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head.last = null;
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}
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return ans;
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}
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}
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private HashMap<Integer, Node> keyNodeMap;
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private DoubleLinkedList nodeList;
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private final int capacity;
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public LRUCache(int cap) {
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keyNodeMap = new HashMap<>();
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nodeList = new DoubleLinkedList();
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capacity = cap;
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}
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public int get(int key) {
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if (keyNodeMap.containsKey(key)) {
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Node ans = keyNodeMap.get(key);
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nodeList.moveNodeToTail(ans);
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return ans.val;
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}
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return -1;
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}
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public void put(int key, int value) {
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if (keyNodeMap.containsKey(key)) {
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Node node = keyNodeMap.get(key);
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node.val = value;
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nodeList.moveNodeToTail(node);
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} else {
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Node newNode = new Node(key, value);
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keyNodeMap.put(key, newNode);
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nodeList.addNode(newNode);
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if (keyNodeMap.size() == capacity + 1) {
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removeMostUnusedCache();
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}
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}
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}
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private void removeMostUnusedCache() {
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Node removeNode = nodeList.removeHead();
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keyNodeMap.remove(removeNode.key);
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}
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}
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}
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