104. Maximum Depth of Binary Tree

104. Maximum Depth of Binary Tree

Leetcode link for this question

Discription:

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.

Analyze:

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

#Generate a binary tree by a list ( like, [1,2,None,4,5,6,None,8,9,10,11,12] ) and return the root node.
def gen_Tree(val_list):
if not val_list:
return
root=TreeNode(val_list.pop(0))
#print root.val
le_list=[root]
while val_list:
tmp=le_list.pop(0)
if val_list:
tmp.left=TreeNode(val_list.pop(0))
if tmp.left.val!=None:
le_list.append(tmp.left)
if val_list:
tmp.right=TreeNode(val_list.pop(0))
if tmp.right.val!=None:
le_list.append(tmp.right)
else:
return root
return root

# print the tree by level
def show_Tree(root):
def print_fun(le):
for i in le:
if i!=None:
print i.val,
else:
print 'None',
print ''
cur_le=[root]
next_le=[]
print_fun(cur_le)
while cur_le:
tmp=cur_le.pop(0)
if tmp!=None:# and tmp.val!=None:
if tmp.left:
next_le.append(tmp.left)
else:
next_le.append(None)
if tmp.right:
next_le.append(tmp.right)
else:
next_le.append(None)
if not cur_le:
cur_le=next_le
print_fun(cur_le)
next_le=[]
if not cur_le:
break
return

root=gen_Tree([1,2,None,4,5,6,None,8,9,10,11,12])
show_Tree(root)

1
2 None
4 5 None None
6 None 8 9
10 11 None None 12 None None None
None None None None None None

Code 1:

class Solution(object):
def maxDepth(self,root):
if not root:
return 0
queue,hei,max_hei=[],1,1
queue.append((root,1))
while queue:
node,hei=queue.pop(0)
max_hei=max(max_hei,hei)
if node.left:
queue.append((node.left,hei+1))
if node.right:
queue.append((node.right,hei+1))
max_hei=max(max_hei,hei)
return max_hei

Submission Result:

Status: Accepted

Runtime: 68 ms

Ranking: beats 71.09%