Solving Invert Binary Tree: Flipping a Binary Tree

The "Invert Binary Tree" problem focuses on inverting a binary tree, effectively flipping it around its center, such that each left child becomes a right child and vice versa.

Problem Statement

Given the root of a binary tree, invert the tree, and return its root.

Example

Consider a binary tree:

The inverted tree is a mirror image of the original tree.

Solution Approach - Recursive Swap

class TreeNode {
  val: number;
  left: TreeNode | null;
  right: TreeNode | null;

  constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
    this.val = val === undefined ? 0 : val;
    this.left = left === undefined ? null : left;
    this.right = right === undefined ? null : right;
  }
}

function invertTree(root: TreeNode | null): TreeNode | null {
  if (root === null) {
    return null;
  }
  [root.left, root.right] = [invertTree(root.right), invertTree(root.left)];
  return root;
}

Breaking Down the Solution

• Recursive Approach: The function invertTree is a recursive solution that inverts each node in the tree.
• Swapping Children: At each node, swap its left and right children.
• Base Case: If a node is null, return null.

Conclusion

Inverting a binary tree is an interesting problem that demonstrates the elegance and simplicity of recursive tree manipulation, showcasing fundamental concepts in binary tree algorithms.