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package class50;
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import java.util.ArrayList;
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import java.util.List;
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import java.util.TreeMap;
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public class Problem_0588_DesignInMemoryFileSystem {
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class FileSystem {
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public class Node {
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// 文件名、目录名
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public String name;
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// content == null 意味着这个节点是目录
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// content != null 意味着这个节点是文件
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public StringBuilder content;
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public TreeMap<String, Node> nexts;
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// 构造目录
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public Node(String n) {
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name = n;
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content = null;
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nexts = new TreeMap<>();
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}
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// 构造文件，c是文件内容
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public Node(String n, String c) {
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name = n;
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content = new StringBuilder(c);
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nexts = new TreeMap<>();
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}
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}
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public Node head;
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public FileSystem() {
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head = new Node("");
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}
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public List<String> ls(String path) {
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List<String> ans = new ArrayList<>();
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Node cur = head;
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String[] parts = path.split("/");
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int n = parts.length;
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for (int i = 1; i < n; i++) {
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if (!cur.nexts.containsKey(parts[i])) {
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return ans;
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}
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cur = cur.nexts.get(parts[i]);
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}
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// cur结束了！来到path最后的节点，该返回了
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// ls a/b/c cur 来到c目录
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// 如果c是目录，那么就要返回c下面所有的东西！
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// 如果c是文件，那么就值返回c
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if (cur.content == null) {
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ans.addAll(cur.nexts.keySet());
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} else {
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ans.add(cur.name);
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}
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return ans;
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}
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public void mkdir(String path) {
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Node cur = head;
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String[] parts = path.split("/");
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int n = parts.length;
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for (int i = 1; i < n; i++) {
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if (!cur.nexts.containsKey(parts[i])) {
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cur.nexts.put(parts[i], new Node(parts[i]));
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}
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cur = cur.nexts.get(parts[i]);
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}
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}
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public void addContentToFile(String path, String content) {
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Node cur = head;
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String[] parts = path.split("/");
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int n = parts.length;
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for (int i = 1; i < n - 1; i++) {
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if (!cur.nexts.containsKey(parts[i])) {
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cur.nexts.put(parts[i], new Node(parts[i]));
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}
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cur = cur.nexts.get(parts[i]);
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}
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// 来到的是倒数第二的节点了！注意for！
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if (!cur.nexts.containsKey(parts[n - 1])) {
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cur.nexts.put(parts[n - 1], new Node(parts[n - 1], ""));
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}
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cur.nexts.get(parts[n - 1]).content.append(content);
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}
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public String readContentFromFile(String path) {
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Node cur = head;
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String[] parts = path.split("/");
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int n = parts.length;
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for (int i = 1; i < n; i++) {
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if (!cur.nexts.containsKey(parts[i])) {
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cur.nexts.put(parts[i], new Node(parts[i]));
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}
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cur = cur.nexts.get(parts[i]);
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}
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return cur.content.toString();
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}
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}
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}
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