题目 Write a program to find the node at which the intersection of two singly linked lists begins. For example, the following two linked lists: begin to intersect at node c1. Notes: If the two linked lists have no intersection at all, return null. The…

Write a program to find the node at which the intersection of two singly linked lists begins. For example, the following two linked lists: A: a1 → a2 ↘ c1 → c2 → c3 ↗ B: b1 → b2 → b3 begin to intersect at node c1. Notes: If the two linked lists have…

Write a program to find the node at which the intersection of two singly linked lists begins. For example, the following two linked lists: A: a1 → a2 ↘ c1 → c2 → c3 ↗ B: b1 → b2 → b3 begin to intersect at node c1/** * Definition for singly-linked lis…

Write a program to find the node at which the intersection of two singly linked lists begins. For example, the following two linked lists: A: a1 → a2 ↘ c1 → c2 → c3 ↗ B: b1 → b2 → b3 begin to intersect at node c1. 题意: 给两个可能相交的链表,求出其交点位置. 思路: 1.将其中一条链…

此题扩展:链表有环,如何判断相交? 参考资料: 编程判断两个链表是否相交 面试精选:链表问题集锦 题目链接 题目要求: Write a program to find the node at which the intersection of two singly linked lists begins. For example, the following two linked lists: A: a1 → a2 ↘ c1 → c2 → c3 ↗ B: b1 → b2 → b3 begin t…

Write a program to find the node at which the intersection of two singly linked lists begins. For example, the following two linked lists: A: a1 → a2 ↘ c1 → c2 → c3 ↗ B: b1 → b2 → b3 begin to intersect at node c1. Notes: If the two linked lists have…

Intersection of Two Linked Lists Write a program to find the node at which the intersection of two singly linked lists begins. For example, the following two linked lists: A: a1 → a2 ↘ c1 → c2 → c3 ↗ B: b1 → b2 → b3 begin to intersect at node c1. Not…

Intersection of Two Linked Lists Write a program to find the node at which the intersection of two singly linked lists begins. For example, the following two linked lists: A:          a1 → a2                   ↘                     c1 → c2 → c3      …

160. Intersection of Two Linked Lists[easy] Write a program to find the node at which the intersection of two singly linked lists begins. For example, the following two linked lists: A: a1 → a2 ↘ c1 → c2 → c3 ↗ B: b1 → b2 → b3 begin to intersect at n…

题目 Follow up for H-Index: What if the citations array is sorted in ascending order? Could you optimize your algorithm? 分析 同LeetCode(274)H-Index第二个版本,给定引用数量序列为递增的:这就省略了我们的第一个排序步骤: O(n)的时间复杂度,遍历一次即可. AC代码 class Solution { public: int hIndex(vector<int>…

题目 Given an array of integers, find out whether there are two distinct indices i and j in the array such that the difference between nums[i] and nums[j] is at most t and the difference between i and j is at most k. 分析 题目描述:给定一个整数序列,查找是否存在两个下标分别为i和j的元…

题目 Follow up for "Find Minimum in Rotated Sorted Array": What if duplicates are allowed? Would this affect the run-time complexity? How and why? Suppose a sorted array is rotated at some pivot unknown to you beforehand. (i.e., 0 1 2 4 5 6 7 migh…

题目 Say you have an array for which the ith element is the price of a given stock on day i. Design an algorithm to find the maximum profit. You may complete as many transactions as you like (ie, buy one and sell one share of the stock multiple times).…

题目 Given a binary tree struct TreeLinkNode { TreeLinkNode *left; TreeLinkNode *right; TreeLinkNode *next; } Populate each next pointer to point to its next right node. If there is no next right node, the next pointer should be set to NULL. Initially,…

题目 Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum. For example: Given the below binary tree and sum = 22, 分析 本题目与上一题LeetCode(112) Path Sum虽然类型相同,但是需要在以前的基础上,多做处理一些: 与Path Sum相比,本题是求出路径,所以,在找到满足的路…

题目 Given a binary tree, return the bottom-up level order traversal of its nodes' values. (ie, from left to right, level by level from leaf to root). For example: Given binary tree {3,9,20,#,#,15,7}, return its bottom-up level order traversal as: 分析 与…

题目 There are two sorted arrays nums1 and nums2 of size m and n respectively. Find the median of the two sorted arrays. The overall run time complexity should be O(log (m+n)). 分析 给定两个有序序列,要求两个序列综合后的中位数.关键:算法复杂度T(n)=O(log(m+n)) 该问题的关键就在于复杂度的限制,有了这个限制,就…

Leetcode(1)两数之和 [题目表述]: 给定一个整数数组 nums 和一个目标值 target,请你在该数组中找出和为目标值的那 两个 整数,并返回他们的数组下标.你可以假设每种输入只会对应一个答案.但是,你不能重复利用这个数组中同样的元素. 第一种方法:暴力 执行用时:5352 ms: 内存消耗:12.9MB 效果:非常差 class Solution(object): def twoSum(self, nums, target): """ :type nums:…

Leetcode(2)两数相加 [题目表述]: 给出两个 非空 的链表用来表示两个非负的整数.其中,它们各自的位数是按照 逆序 的方式存储的,并且它们的每个节点只能存储 一位 数字. 如果,我们将这两个数相加起来,则会返回一个新的链表来表示它们的和.您可以假设除了数字 0 之外,这两个数都不会以 0 开头. 第一种方法:大众解法 执行用时:80 ms: 内存消耗:12.2MB # Definition for singly-linked list. # class ListNode(object…

Leetcode(3)无重复字符的最长子串 [题目表述]: 给定一个字符串,请你找出其中不含有重复字符的 最长子串 的长度. 第一种方法:暴力 执行用时:996 ms: 内存消耗:12.9MB 效果:太差 class Solution(object): def lengthOfLongestSubstring(self, s): """ :type s: str :rtype: int """ Maxsize=0 res='' if len(s)…

Leetcode(4)寻找两个有序数组的中位数 [题目表述]: 给定两个大小为 m 和 n 的有序数组 nums1 和* nums2. 请你找出这两个有序数组的中位数,并且要求算法的时间复杂度为 O(log(m + n)). 你可以假设 nums1* 和 nums2 不会同时为空. 第一种方法:list拼接排列取中位数 执行用时:116 ms : 内存消耗:11.8MB 效果:还行 class Solution(object): def findMedianSortedArrays(self,…

Leetcode(4)寻找两个有序数组的中位数 [题目表述]: 给定一个字符串 s,找到 s 中 最长 的回文子串.你可以假设 s 的最大长度为 1000.' 第一种方法:未完成:利用回文子串的特点 一开始我的思路如下:回文子串的特点是首尾字母相同,所以我对每一个字母都找到位于它后面的相同字母,利用切片判断这一段是否为回文子串(str[i:j]==str[i:j][::-1]).时间复杂度很高,主要是因为str.find操作非常耗时. class Solution(object): def lo…

Leetcode(6)Z字形变换 [题目表述]: 将一个给定字符串根据给定的行数,以从上往下.从左到右进行 Z 字形排列. 比如输入字符串为 "LEETCODEISHIRING" 行数为 3 时,排列如下: L C I R E T O E S I I G E D H N 之后,你的输出需要从左往右逐行读取,产生出一个新的字符串,比如:"LCIRETOESIIGEDHN". 第一次:找下标规律按行输出 执行用时:84 ms: 内存消耗:11.8MB 效果:还行 cla…

Leetcode(6)Z字形变换 [题目表述]: 给出一个 32 位的有符号整数,你需要将这个整数中每位上的数字进行反转. 第一次:转字符串处理 执行用时:40 ms: 内存消耗:11.6MB 效果:很好 class Solution(object): def reverse(self, x): """ :type x: int :rtype: int """ if x>=0: r=str(x) r=r[::-1] n=int(r) els…

Leetcode(8)字符串转换整数 [题目表述]: 请你来实现一个 atoi 函数,使其能将字符串转换成整数. 首先,该函数会根据需要丢弃无用的开头空格字符,直到寻找到第一个非空格的字符为止. 当我们寻找到的第一个非空字符为正或者负号时,则将该符号与之后面尽可能多的连续数字组合起来,作为该整数的正负号:假如第一个非空字符是数字,则直接将其与之后连续的数字字符组合起来,形成整数. 该字符串除了有效的整数部分之后也可能会存在多余的字符,这些字符可以被忽略,它们对于函数不应该造成影响. 注意:假如该…

Leetcode(9)回文数 [题目表述]: 判断一个整数是否是回文数.回文数是指正序(从左向右)和倒序(从右向左)读都是一样的整数. 第一次:直接全部转 执行用时:148 ms: 内存消耗:13.4MB 效果:还行 class Solution: def isPalindrome(self, x: int) -> bool: s=str(x) if s==s[::-1]: return True else: return False 第二种方法:反转一半数字 执行用时:156 ms: 内存消耗…

Leetcode(10)正则表达式匹配 [题目表述]: 给定一个字符串 (s) 和一个字符模式 (p).实现支持 '.' 和 '*' 的正则表达式匹配. '.' 匹配任意单个字符. '*' 匹配零个或多个前面的元素. 匹配应该覆盖整个字符串 (s) ,而不是部分字符串. 第一次:未完成(未能解决.*问题 class Solution: def isMatch(self, s: str, p: str) -> bool: index_s=0 index_p=0 form_num='' if len…

160. Intersection of Two Linked Lists Easy Write a program to find the node at which the intersection of two singly linked lists begins. For example, the following two linked lists: begin to intersect at node c1. Example 1: Input: intersectVal = 8, l…

160. Intersection of Two Linked Lists(Easy) 题目地址https://leetcode.com/problems/intersection-of-two-linked-lists/ Write a program to find the node at which the intersection of two singly linked lists begins. For example, the following two linked lists:…

Write a program to find the node at which the intersection of two singly linked lists begins. Notice If the two linked lists have no intersection at all, return null. The linked lists must retain their original structure after the function returns. Y…