[LeetCode] 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].java

/**
 * Definition for binary tree
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public int minDepth(TreeNode root) {
        // Start typing your Java solution below
        // DO NOT write main() function
        if(root == null) return 0;
        if(root.left == null && root.right == null) return 1;
        else if(root.left != null && root.right != null)
            return Math.min(minDepth(root.left), minDepth(root.right)) + 1;
        else{
            if(root.left == null) return minDepth(root.right) + 1;
            else return minDepth(root.left) + 1;
        }
    }
}