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Feb 22, 2025
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solution in java lang #1028 #4096

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f5c1264
solution in java lang #1028
PATILYASH007 Feb 22, 2025
04ab687
Add Java solution to README_EN.md
yanglbme Feb 22, 2025
25433ce
Add Java solution to README.md
yanglbme Feb 22, 2025
9283bda
Remove trailing whitespace in Solution.java
yanglbme Feb 22, 2025
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57 changes: 57 additions & 0 deletions solution/1000-1099/1028.Recover a Tree From Preorder Traversal/README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -74,6 +74,63 @@ tags:

<!-- tabs:start -->

#### Java

```java
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode() {}
* TreeNode(int val) { this.val = val; }
* TreeNode(int val, TreeNode left, TreeNode right) {
* this.val = val;
* this.left = left;
* this.right = right;
* }
* }
*/
class Solution {
public TreeNode recoverFromPreorder(String traversal) {
Stack<TreeNode> stack = new Stack<>();
int i = 0;

while (i < traversal.length()) {
int depth = 0;
while (i < traversal.length() && traversal.charAt(i) == '-') {
depth++;
i++;
}

int num = 0;
while (i < traversal.length() && Character.isDigit(traversal.charAt(i))) {
num = num * 10 + (traversal.charAt(i) - '0');
i++;
}

// Create the new node
TreeNode newNode = new TreeNode(num);

while (stack.size() > depth) {
stack.pop();
}
if (!stack.isEmpty()) {
if (stack.peek().left == null) {
stack.peek().left = newNode;
} else {
stack.peek().right = newNode;
}
}

stack.push(newNode);
}
return stack.isEmpty() ? null : stack.get(0);
}
}
```

#### C++

```cpp
Expand Down
57 changes: 57 additions & 0 deletions solution/1000-1099/1028.Recover a Tree From Preorder Traversal/README_EN.md
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -69,6 +69,63 @@ tags:

<!-- tabs:start -->

#### Java

```java
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode() {}
* TreeNode(int val) { this.val = val; }
* TreeNode(int val, TreeNode left, TreeNode right) {
* this.val = val;
* this.left = left;
* this.right = right;
* }
* }
*/
class Solution {
public TreeNode recoverFromPreorder(String traversal) {
Stack<TreeNode> stack = new Stack<>();
int i = 0;

while (i < traversal.length()) {
int depth = 0;
while (i < traversal.length() && traversal.charAt(i) == '-') {
depth++;
i++;
}

int num = 0;
while (i < traversal.length() && Character.isDigit(traversal.charAt(i))) {
num = num * 10 + (traversal.charAt(i) - '0');
i++;
}

// Create the new node
TreeNode newNode = new TreeNode(num);

while (stack.size() > depth) {
stack.pop();
}
if (!stack.isEmpty()) {
if (stack.peek().left == null) {
stack.peek().left = newNode;
} else {
stack.peek().right = newNode;
}
}

stack.push(newNode);
}
return stack.isEmpty() ? null : stack.get(0);
}
}
```

#### C++

```cpp
Expand Down
52 changes: 52 additions & 0 deletions solution/1000-1099/1028.Recover a Tree From Preorder Traversal/Solution.java
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Original file line number Diff line number Diff line change
@@ -0,0 +1,52 @@
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode() {}
* TreeNode(int val) { this.val = val; }
* TreeNode(int val, TreeNode left, TreeNode right) {
* this.val = val;
* this.left = left;
* this.right = right;
* }
* }
*/
class Solution {
public TreeNode recoverFromPreorder(String traversal) {
Stack<TreeNode> stack = new Stack<>();
int i = 0;

while (i < traversal.length()) {
int depth = 0;
while (i < traversal.length() && traversal.charAt(i) == '-') {
depth++;
i++;
}

int num = 0;
while (i < traversal.length() && Character.isDigit(traversal.charAt(i))) {
num = num * 10 + (traversal.charAt(i) - '0');
i++;
}

// Create the new node
TreeNode newNode = new TreeNode(num);

while (stack.size() > depth) {
stack.pop();
}
if (!stack.isEmpty()) {
if (stack.peek().left == null) {
stack.peek().left = newNode;
} else {
stack.peek().right = newNode;
}
}

stack.push(newNode);
}
return stack.isEmpty() ? null : stack.get(0);
}
}