Minimum Depth of Binary Tree
題意:
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.
解題思路:
中間兩個if需要,因為要防止 [1,2]這種情況
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
public class Solution {
public int minDepth(TreeNode root) {
if (root == null) {
return 0;
}
if (root.left == null) {
return minDepth(root.right) + 1;
}
if (root.right == null) {
return minDepth(root.left) + 1;
}
return Math.min(minDepth(root.left), minDepth(root.right)) + 1;
}
}