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.
1 public class Solution { 2 public int minDepth(TreeNode root) { 3 if(root==null) return 0; 4 int left = minDepth(root.left); 5 int right = minDepth(root.right); 6 if(left==0 && right ==0) return 1; 7 if(left ==0) left=Integer.MAX_VALUE; 8 if(right==0) right=Integer.MIN_VALUE; 9 return Math.min(right,left)+1; 10 } 11 }