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1948. Delete Duplicate Folders in System solution #4578

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385da57
Create Solution.java
rajenderthota Jul 20, 2025
d25460d
Update README.md
rajenderthota Jul 20, 2025
db9eb43
Update README_EN.md
rajenderthota Jul 20, 2025
f83ac58
style: format code and docs with prettier
rajenderthota Jul 20, 2025
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69 changes: 69 additions & 0 deletions solution/1900-1999/1948.Delete Duplicate Folders in System/README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -135,6 +135,75 @@ tags:
#### Java

```java
class Solution {
static class TrieNode {
Map<String, TrieNode> children = new HashMap<>();
String name;
boolean isDeleted = false;

TrieNode(String name) {
this.name = name;
}
}

Map<String, List<TrieNode>> serialMap = new HashMap<>();

public List<List<String>> deleteDuplicateFolder(List<List<String>> paths) {
TrieNode root = new TrieNode("");

// Step 1: Build the folder trie
for (List<String> path : paths) {
TrieNode curr = root;
for (String folder : path) {
curr.children.putIfAbsent(folder, new TrieNode(folder));
curr = curr.children.get(folder);
}
}

// Step 2: Serialize and collect duplicates
serialize(root);

// Step 3: Mark duplicate folders
for (List<TrieNode> group : serialMap.values()) {
if (group.size() > 1) {
for (TrieNode node : group) {
node.isDeleted = true;
}
}
}

// Step 4: Collect remaining paths
List<List<String>> result = new ArrayList<>();
dfs(root, new ArrayList<>(), result);
return result;
}

private String serialize(TrieNode node) {
if (node.children.isEmpty()) return "";

List<String> parts = new ArrayList<>();
for (String childName : node.children.keySet().stream().sorted().toList()) {
TrieNode child = node.children.get(childName);
String sub = serialize(child);
parts.add(childName + "[" + sub + "]");
}

String serial = String.join("", parts);
serialMap.computeIfAbsent(serial, k -> new ArrayList<>()).add(node);
return serial;
}

private void dfs(TrieNode node, List<String> path, List<List<String>> result) {
for (TrieNode child : node.children.values()) {
if (!child.isDeleted) {
path.add(child.name);
result.add(new ArrayList<>(path));
dfs(child, path, result);
path.remove(path.size() - 1);
}
}
}
}

```

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69 changes: 69 additions & 0 deletions solution/1900-1999/1948.Delete Duplicate Folders in System/README_EN.md
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Original file line number Diff line number Diff line change
Expand Up @@ -114,6 +114,75 @@ Note that the returned array can be in a different order as the order does not m
#### Java

```java
class Solution {
static class TrieNode {
Map<String, TrieNode> children = new HashMap<>();
String name;
boolean isDeleted = false;

TrieNode(String name) {
this.name = name;
}
}

Map<String, List<TrieNode>> serialMap = new HashMap<>();

public List<List<String>> deleteDuplicateFolder(List<List<String>> paths) {
TrieNode root = new TrieNode("");

// Step 1: Build the folder trie
for (List<String> path : paths) {
TrieNode curr = root;
for (String folder : path) {
curr.children.putIfAbsent(folder, new TrieNode(folder));
curr = curr.children.get(folder);
}
}

// Step 2: Serialize and collect duplicates
serialize(root);

// Step 3: Mark duplicate folders
for (List<TrieNode> group : serialMap.values()) {
if (group.size() > 1) {
for (TrieNode node : group) {
node.isDeleted = true;
}
}
}

// Step 4: Collect remaining paths
List<List<String>> result = new ArrayList<>();
dfs(root, new ArrayList<>(), result);
return result;
}

private String serialize(TrieNode node) {
if (node.children.isEmpty()) return "";

List<String> parts = new ArrayList<>();
for (String childName : node.children.keySet().stream().sorted().toList()) {
TrieNode child = node.children.get(childName);
String sub = serialize(child);
parts.add(childName + "[" + sub + "]");
}

String serial = String.join("", parts);
serialMap.computeIfAbsent(serial, k -> new ArrayList<>()).add(node);
return serial;
}

private void dfs(TrieNode node, List<String> path, List<List<String>> result) {
for (TrieNode child : node.children.values()) {
if (!child.isDeleted) {
path.add(child.name);
result.add(new ArrayList<>(path));
dfs(child, path, result);
path.remove(path.size() - 1);
}
}
}
}

```

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69 changes: 69 additions & 0 deletions solution/1900-1999/1948.Delete Duplicate Folders in System/Solution.java
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Original file line number Diff line number Diff line change
@@ -0,0 +1,69 @@
class Solution {
static class TrieNode {
Map<String, TrieNode> children = new HashMap<>();
String name;
boolean isDeleted = false;

TrieNode(String name) {
this.name = name;
}
}

Map<String, List<TrieNode>> serialMap = new HashMap<>();

public List<List<String>> deleteDuplicateFolder(List<List<String>> paths) {
TrieNode root = new TrieNode("");

// Step 1: Build the folder trie
for (List<String> path : paths) {
TrieNode curr = root;
for (String folder : path) {
curr.children.putIfAbsent(folder, new TrieNode(folder));
curr = curr.children.get(folder);
}
}

// Step 2: Serialize and collect duplicates
serialize(root);

// Step 3: Mark duplicate folders
for (List<TrieNode> group : serialMap.values()) {
if (group.size() > 1) {
for (TrieNode node : group) {
node.isDeleted = true;
}
}
}

// Step 4: Collect remaining paths
List<List<String>> result = new ArrayList<>();
dfs(root, new ArrayList<>(), result);
return result;
}

private String serialize(TrieNode node) {
if (node.children.isEmpty()) return "";

List<String> parts = new ArrayList<>();
for (String childName : node.children.keySet().stream().sorted().toList()) {
TrieNode child = node.children.get(childName);
String sub = serialize(child);
parts.add(childName + "[" + sub + "]");
}

String serial = String.join("", parts);
serialMap.computeIfAbsent(serial, k -> new ArrayList<>()).add(node);
return serial;
}

private void dfs(TrieNode node, List<String> path, List<List<String>> result) {
for (TrieNode child : node.children.values()) {
if (!child.isDeleted) {
path.add(child.name);
result.add(new ArrayList<>(path));
dfs(child, path, result);
path.remove(path.size() - 1);
}
}
}
}