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Leetcode[104, 111] Maximum/Minimum Depth of Binary Tree

07 Nov 2015

###Task1 Given a binary tree, find its maximum depth.

The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

###Python

# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution(object):
    def maxDepth(self, root):
        """
        :type root: TreeNode
        :rtype: int
        """
        if not root:
            return 0
        return max(self.maxDepth(root.left), self.maxDepth(root.right)) + 1

###Java

/**
/**
 * 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 maxDepth(TreeNode root) {
        if (root == null) {
        	return 0;
        }
        int left = maxDepth(root.left);
        int right = maxDepth(root.right);
        int max = Math.max(left, right);

        return max + 1;
    }
}

###Points

###Task2 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. ###Python

# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution(object):
    def minDepth(self, root):
        """
        :type root: TreeNode
        :rtype: int
        """
        if not root:
            return 0
        if not root.left and not root.right:
            return 1
        if not root.left:
            return self.minDepth(root.right) + 1
        if not root.right:
            return self.minDepth(root.left) + 1
        return min(self.minDepth(root.left), self.minDepth(root.right)) + 1

###Java

/**
 * 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;
        }
        int left = minDepth(root.left);
        int right = minDepth(root.right);

        if (left == 0 && right == 0) {
        	return 1;
        }
        if (left == 0) {
        	return 1 + right;
        }
        if (right == 0) {
        	return 1 + left;
        }
        return 1 + Math.min(left, right);
    }
}

###Points

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