Commit 75171a3

committed

solves binary tree level order traversal in java

1 parent ea4643a commit 75171a3Copy full SHA for 75171a3

File tree

+39

-1

lines changed

+39

-1

lines changed

Lines changed: 1 addition & 1 deletion

Original file line number	Diff line number	Diff line change
`@@ -93,7 +93,7 @@`
`93`	`93`	`\| 99 \| [Recover Binary Search Tree](https://leetcode.com/problems/recover-binary-search-tree) \| \| \|`
`94`	`94`	`\| 100 \| [Same Tree](https://leetcode.com/problems/same-tree) \| [![Java](assets/java.png)](src/SameTree.java) [![Python](assets/python.png)](python/same_tree.py) \| \|`
`95`	`95`	`\| 101 \| [Symmetric Tree](https://leetcode.com/problems/symmetric-tree) \| [![Java](assets/java.png)](src/SymmetricTree.java) [![Python](assets/python.png)](python/symmetric_tree.py) \| \|`
`96`		`-\| 102 \| [Binary Tree Level Order Traversal](https://leetcode.com/problems/binary-tree-level-order-traversal) \| \| \|`
	`96`	`+\| 102 \| [Binary Tree Level Order Traversal](https://leetcode.com/problems/binary-tree-level-order-traversal) \| [![Java](assets/java.png)](src/BinaryTreeLevelOrderTraversal.java) \| \|`
`97`	`97`	`\| 103 \| [Binary Tree Zigzag Level Order Traversal](https://leetcode.com/problems/binary-tree-zigzag-level-order-traversal) \| \| \|`
`98`	`98`	`\| 104 \| [Maximum Depth of Binary Tree](https://leetcode.com/problems/maximum-depth-of-binary-tree) \| [![Java](assets/java.png)](src/MaximumDepthOfBinaryTree.java) [![Python](assets/python.png)](python/maximum_depth_of_binary_tree.py) \| \|`
`99`	`99`	`\| 105 \| [Construct Binary Tree from Preorder and Inorder Traversal](https://leetcode.com/problems/construct-binary-tree-from-preorder-and-inorder-traversal) \| \| \|`

Lines changed: 38 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,38 @@`
	`1`	`+// https://leetcode.com/problems/binary-tree-level-order-traversal`
	`2`	`+// T: O(n)`
	`3`	`+// S: O(n)`
	`4`	`+`
	`5`	`+import java.util.ArrayList;`
	`6`	`+import java.util.LinkedList;`
	`7`	`+import java.util.List;`
	`8`	`+import java.util.Queue;`
	`9`	`+`
	`10`	`+public class BinaryTreeLevelOrderTraversal {`
	`11`	`+ public List<List<Integer>> levelOrder(TreeNode root) {`
	`12`	`+ if (root == null) {`
	`13`	`+ return List.of();`
	`14`	`+ }`
	`15`	`+`
	`16`	`+ final Queue<TreeNode> queue = new LinkedList<>();`
	`17`	`+ queue.add(root);`
	`18`	`+ queue.add(null);`
	`19`	`+ final List<List<Integer>> result = new ArrayList<>();`
	`20`	`+ List<Integer> level = new ArrayList<>();`
	`21`	`+`
	`22`	`+ while (!queue.isEmpty()) {`
	`23`	`+ TreeNode current = queue.poll();`
	`24`	`+ if (current == null) {`
	`25`	`+ result.add(level);`
	`26`	`+ if (!queue.isEmpty()) {`
	`27`	`+ queue.add(null);`
	`28`	`+ level = new ArrayList<>();`
	`29`	`+ }`
	`30`	`+ } else {`
	`31`	`+ level.add(current.val);`
	`32`	`+ if (current.left != null) queue.add(current.left);`
	`33`	`+ if (current.right != null) queue.add(current.right);`
	`34`	`+ }`
	`35`	`+ }`
	`36`	`+ return result;`
	`37`	`+ }`
	`38`	`+}`

Comments

(0)