次の右ノードleetcode-117-各ノードポインタを埋める②

--- ---復元コンテンツ始まります

件名の説明：

 

 

 方法の一つ：レベルトラバース

"""
# Definition for a Node.
class Node:
    def __init__(self, val, left, right, next):
        self.val = val
        self.left = left
        self.right = right
        self.next = next
"""
class Solution:
    def connect(self, root: 'Node') -> 'Node':
        if not root:
            return
        stack = [root]
        #ans = []
        while stack:
            tem_stack=[]
            #tem_ans = []
            for i in stack:
                tem_ans.append(i.val)
                if i.left:
                    tem_stack.append(i.left)
                if i.right:
                    tem_stack.append(i.right)
            if len(tem_stack)>1:
                for i in range(len(tem_stack)-1):
                    tem_stack[i].next = tem_stack[i+1]
            stack = tem_stack
            #ans.append(tem_ans)
        return root

方法二：迭代

class Solution:
    def connect(self, root: 'Node') -> 'Node':
        cur = root 
        head = None 
        tail = None 
        while cur: 
            while cur: 
                if cur.left: 
                    if not head: 
                        head = cur.left 
                        tail = cur.left 
                    else: 
                        tail.next = cur.left 
                        tail = tail.next 
                if cur.right: 
                    if not head: 
                        head = cur.right 
                        tail = cur.right 
                    else: 
                        tail.next = cur.right 
                        tail = tail.next 
                cur = cur.next 
            cur = head 
            head = None 
            tail = None 
        return root

 

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