Minimum Depth of Binary Tree

Given a binary tree, find its minimum depth.

The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.

Solution:

  1. /**
  2.  * Definition for a binary tree node.
  3.  * public class TreeNode {
  4.  *     int val;
  5.  *     TreeNode left;
  6.  *     TreeNode right;
  7.  *     TreeNode(int x) { val = x; }
  8.  * }
  9.  */
  10. public class Solution {
  11.   public int minDepth(TreeNode root) {
  12.     if (root == null)
  13.       return 0;
  15.     if (root.left == null)
  16.       return 1 + minDepth(root.right);
  18.     if (root.right == null)
  19.       return 1 + minDepth(root.left);
  21.     return 1 + Math.min(minDepth(root.left), minDepth(root.right));
  22.   }
  23. }