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binary tree 的inorder 和preorder 和postorder

时间: 2024-11-01 19:08:08 浏览: 62

In-order, pre-order, and post-order traversals are methods to visit each node in a binary tree in a specific sequence. 1. **In-order traversal**[^1]: Also known as the "left-root-right" order, it visits the left subtree first, then the root node, and finally the right subtree. This ensures that for a binary search tree, the output will be sorted. ```java // Example for In-order traversal void inorderTraversal(TreeNode root) { if (root != null) { inorderTraversal(root.left); System.out.print(root.val + " "); // Visit the current node inorderTraversal(root.right); } } ``` 2. **Pre-order traversal**: The "root-left-right" order, starts by visiting the root, followed by the left subtree, and then the right subtree. ```java // Example for Pre-order traversal void preorderTraversal(TreeNode root) { if (root != null) { System.out.print(root.val + " "); // Visit the current node first preorderTraversal(root.left); preorderTraversal(root.right); } } ``` 3. **Post-order traversal**: The "left-right-root" order, visits the left subtree, then the right subtree, and finally the root node. ```java // Example for Post-order traversal void postorderTraversal(TreeNode root) { if (root != null) { postorderTraversal(root.left); postorderTraversal(root.right); System.out.print(root.val + " "); // Visit the current node last } } ```

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