9月

Author: junncao

160.相交链表.py

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+#
+# @lc app=leetcode.cn id=160 lang=python
+#
+# [160] 相交链表
+#
+# Definition for singly-linked list.
+# class ListNode(object):
+#     def __init__(self, x):
+#         self.val = x
+#         self.next = None
+
+class Solution(object):
+    def getIntersectionNode(self, headA, headB):
+        """
+        :type head1, head1: ListNode
+        :rtype: ListNode
+        """
+        
+

24.两两交换链表中的节点.py

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+#
+# @lc app=leetcode.cn id=24 lang=python
+#
+# [24] 两两交换链表中的节点
+#
+# https://leetcode-cn.com/problems/swap-nodes-in-pairs/description/
+#
+# algorithms
+# Medium (62.13%)
+# Likes:    283
+# Dislikes: 0
+# Total Accepted:    39.4K
+# Total Submissions: 63.5K
+# Testcase Example:  '[1,2,3,4]'
+#
+# 给定一个链表，两两交换其中相邻的节点，并返回交换后的链表。
+# 
+# 你不能只是单纯的改变节点内部的值，而是需要实际的进行节点交换。
+# 
+# 
+# 
+# 示例:
+# 
+# 给定 1->2->3->4, 你应该返回 2->1->4->3.
+# 
+# 
+#
+# Definition for singly-linked list.
+# class ListNode(object):
+#     def __init__(self, x):
+#         self.val = x
+#         self.next = None
+
+class Solution(object):
+    def swapPairs(self, head):
+        """
+        :type head: ListNode
+        :rtype: ListNode
+        """
+        

46.全排列.py

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+#
+# @lc app=leetcode.cn id=46 lang=python
+#
+# [46] 全排列
+#
+# https://leetcode-cn.com/problems/permutations/description/
+#
+# algorithms
+# Medium (71.57%)
+# Likes:    376
+# Dislikes: 0
+# Total Accepted:    46.1K
+# Total Submissions: 64.2K
+# Testcase Example:  '[1,2,3]'
+#
+# 给定一个没有重复数字的序列，返回其所有可能的全排列。
+# 
+# 示例:
+# 
+# 输入: [1,2,3]
+# 输出:
+# [
+# ⁠ [1,2,3],
+# ⁠ [1,3,2],
+# ⁠ [2,1,3],
+# ⁠ [2,3,1],
+# ⁠ [3,1,2],
+# ⁠ [3,2,1]
+# ]
+# 
+#
+class Solution(object):
+    def permute(self, nums):
+        """
+        :type nums: List[int]
+        :rtype: List[List[int]]
+        """
+        
+        def backtrack(nums,path):
+            if not nums:
+                res.append(path)
+            for i in xrange(len(nums)):
+                backtrack(nums[:i]+nums[i+1:],path+[nums[i]])
+        res=[]
+        backtrack(nums,[])
+        return res

47.全排列-ii.py

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+#
+# @lc app=leetcode.cn id=47 lang=python
+#
+# [47] 全排列 II
+#
+# https://leetcode-cn.com/problems/permutations-ii/description/
+#
+# algorithms
+# Medium (53.97%)
+# Likes:    159
+# Dislikes: 0
+# Total Accepted:    22.6K
+# Total Submissions: 41.6K
+# Testcase Example:  '[1,1,2]'
+#
+# 给定一个可包含重复数字的序列，返回所有不重复的全排列。
+# 
+# 示例:
+# 
+# 输入: [1,1,2]
+# 输出:
+# [
+# ⁠ [1,1,2],
+# ⁠ [1,2,1],
+# ⁠ [2,1,1]
+# ]
+# 
+#
+class Solution(object):
+    def permuteUnique(self, nums):
+        """
+        :type nums: List[int]
+        :rtype: List[List[int]]
+        """
+        def backtrack(nums,path):
+            if not nums:
+                res.append(path)
+                return
+            for i in xrange(len(nums)):
+                if i>=1 and nums[i]==nums[i-1]:
+                    continue
+                backtrack(nums[:i]+nums[i+1:],path+[nums[i]])
+        res=[]
+        nums.sort()
+        backtrack(nums,[])
+        return res

94.二叉树的中序遍历.py

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+#
+# @lc app=leetcode.cn id=94 lang=python
+#
+# [94] 二叉树的中序遍历
+#
+# https://leetcode-cn.com/problems/binary-tree-inorder-traversal/description/
+#
+# algorithms
+# Medium (67.86%)
+# Likes:    277
+# Dislikes: 0
+# Total Accepted:    59.4K
+# Total Submissions: 87.5K
+# Testcase Example:  '[1,null,2,3]'
+#
+# 给定一个二叉树，返回它的中序 遍历。
+# 
+# 示例:
+# 
+# 输入: [1,null,2,3]
+# ⁠  1
+# ⁠   \
+# ⁠    2
+# ⁠   /
+# ⁠  3
+# 
+# 输出: [1,3,2]
+# 
+# 进阶: 递归算法很简单，你可以通过迭代算法完成吗？
+# 
+#
+# 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 inorderTraversal(self, root):
+        """
+        :type root: TreeNode
+        :rtype: List[int]
+        """
+        
+