LeetCode第六天

83. 删除排序链表中的重复元素

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution:
    def deleteDuplicates(self, head):
        """
        :type head: ListNode
        :rtype: ListNode
        """
        #不带头节点
        if(head==None):
            return head
        cur=head
        while(cur.next):
            if(cur.val==cur.next.val):
                cur.next=cur.next.next
            else:
                cur=cur.next
        return head

88. 合并两个有序数组

class Solution:
    def merge(self, nums1, m, nums2, n):
        """
        :type nums1: List[int]
        :type m: int
        :type nums2: List[int]
        :type n: int
        :rtype: void Do not return anything, modify nums1 in-place instead.
        """
        while m>0 and n>0:
            if nums1[m-1]>nums2[n-1]:
                nums1[m-1+n]=nums1[m-1]
                m=m-1
            else:
                nums1[m-1+n]=nums2[n-1]
                n=n-1
        #如果m==0&n>0,nums1[:n]的数据要用nums2的数据填充
        #如果m>=&n==0,nums1[:m]的数据是剩余的m,不需要再处理
        if n>0:
            nums1[:n]=nums2[:n]

100. 相同的树

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

class Solution:
    def isSameTree(self, p, q):
        """
        :type p: TreeNode
        :type q: TreeNode
        :rtype: bool
        """
        if p==None and q==None:
            return True
        if p==None and q!=None:
            return False
        if p!=None and q==None:
            return False
        if p.val!=q.val:
            return False
        l=self.isSameTree(p.left,q.left)
        r=self.isSameTree(p.right,q.right)
        return l and r      

101.对称二叉树

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

class Solution:
    def isSymmetric(self, root):
        """
        :type root: TreeNode
        :rtype: bool
        """
        if not root:
            return True
        return self.recursiveTree(root.left,root.right)
    def recursiveTree(self,left,right):
        if not left and not right:
            return True
        if not left or not right:
            return False
        if left.val==right.val:
            return self.recursiveTree(left.left,right.right) and self.recursiveTree(left.right,right.left)
        
        return False