[LeetCode] Minimum Depth of Binary Tree

Problem:

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:O(n)

public class Solution {
    public int minDepth(TreeNode root) {
        if(root == null)
            return 0;
        int min = 1;    
        if(root.left == null && root.right ==null ){
            
        }else if(root.left == null){
            min+= minDepth(root.right);
        }else if(root.right == null){
            min+= minDepth(root.left);
        }else{
            min+= Math.min(minDepth(root.left),minDepth(root.right));
        }
        return min;    
    }
}