题目:给定一个数组，它表示了一只股票的价格浮动，第i个元素代表的是股票第i天的价格.设计一个函数，计算出该股票的最大收益，注意，可以多次买入卖出，但下一次买入必须是在本次持有股票卖出之后.比如[1，7，2，3，6，7，6，7]，最大收益为9，第1天买入，第2天卖出，然后第3天买入，第6天卖出，第7天买入，第8天卖出. 分析:该题目的难点在于可以多次买入和卖出. #1 找极值 股票交易取得良好收益的方法是低价买入，高价卖...
题目：二叉树的右视图：给定一棵二叉树，想象自己站在它的右侧，按照从顶部到底部的顺序，返回从右侧所能看到的节点值。思路：借助层序遍历来实现。程序：# Definition for a binary tree node. # class TreeNode: # def __init__(self, x): # self.val = x # self.left = None # self.right = Noneclass Solution:def rightSideView(self, root: TreeNode) -> List[int]:if not root:return []result...
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.python code：# Definition for singly-linked list.# class ListNode:# def __init__(self, x):# self.val = x# ...
LeetCode 1385. Find the Distance Value Between Two Arrays两个数组间的距离值【Easy】【Python】【暴力】ProblemLeetCodeGiven two integer arrays arr1 and arr2, and the integer d, return the distance value between the two arrays.The distance value is defined as the number of elements arr1[i] such that there is not any element arr2[j] where |arr1[i]-arr2[j]| <= d.Example 1:Input: arr1 = [4,5,8], arr2 = ...
# -*- coding: utf8 -*-‘‘‘__author__ = ‘dabay.wang@gmail.com‘https://oj.leetcode.com/problems/longest-substring-without-repeating-characters/Given a string, find the length of the longest substring without repeating characters.For example, the longest substring without repeating letters for "abcabcbb" is "abc",which the length is 3. For "bbbbb" the longest substring is "b", with the length of ...
题目要求的比它的邻居比自己奖励，因此，我们有最少一个多的。所有我们可以找到所有的坑，凹坑例如，存在以下三种情况。找到全部的凹点后，我们就能够从凹点处開始向左右两个方向依次查找递增序列。当中每一个高的都要比相邻的矮的多一个。比方1,2,5,4.我们找到凹点为1 和4，那么从1開始向左没有其它点，我们向右，依次得到2 比1高，2的糖果应该是1的基础上加1。为2， 5比2高，5的糖果是在2的基础上加1，为3。令一个凹点4， 向左，...
Problem: Given a sorted array and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order. You may assume no duplicates in the array. Here are few examples.[1,3,5,6], 5 → 2[1,3,5,6], 2 → 1[1,3,5,6], 7 → 4[1,3,5,6], 0 → 0Solution:二分查找，当找不到时l=r+1,所以根据最后一次l和r的变动来判定应该插入的位置，如果最后一次是l=mid+...
数独规则如下：相当于一个9*9的矩阵代码如下：#特定的九个格内1-9的个数至多为1#依次检查每行，每列，每个子九宫格是否出现重复元素，如果出现返回false，否则返回true.class Solution(object): def isValidSudoku(self, board): """ :type board: List[List[str]] :rtype: bool """ for i in range(len(board)): validate=[] for j in range(len(board[i])):...
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)).Example 1:nums1 = [1, 3] nums2 = [2]The median is 2.0 Example 2:nums1 = [1, 2] nums2 = [3, 4]The median is (2 + 3)/2 = 2.5class Solution(object):def findMedianSortedArrays(self, nums1, nums2):""":type nums1: List[int]:type nums2:...
ProblemLeetCodeGiven the root of a Binary Search Tree (BST), convert it to a Greater Tree such that every key of the original BST is changed to the original key plus sum of all keys greater than the original key in BST.As a reminder, a binary search tree is a tree that satisfies these constraints:The left subtree of a node contains only nodes with keys less than the node‘s key.The right subtree o...
1. Method1class Solution(object):# @return a tuple, (index1, index2)def twoSum(self, num, target):d = {}for i, e in enumerate(num):if e in d:return d[e] + 1, i + 1d[target - e] = is = Solution()print (s.twoSum([0, 2, 1,0], 0))print (s.twoSum([2,4,6],6))Result: (1, 4) (1, 2)2. Method2- TBDxrange=rangeclass Solution(object):# @return a tuple, (index1, index2)def twoSum(self, num, target):dict = {}fo...
该题比较简单，但是这道题有点问题。。。。python中的整数运算没有没有限制，但是在该oj系统中要求对大数输出0（题目并没有说明，但是在test case中可以看出）于是偷了个懒，，，class Solution(object):def reverse(self, x):""":type x: int:rtype: int"""s=‘‘if x==0: return 0if x<0: s+=‘-‘x=abs(x)while x!=0:s+=str(x%10)x=x/10i=int(s) if i>2147483647 or i<-2147483647:return 0return i原文：http://www.cnblogs.co...
题目：Given a sorted array of integers, find the starting and ending position of a given target value.Your algorithm‘s runtime complexity must be in the order of O(log n).If the target is not found in the array, return [-1, -1].For example,Given [5, 7, 7, 8, 8, 10] and target value 8,return [3, 4]. 代码：oj测试通过 Runtime: 91 ms 1class Solution:2# @param A, a list of integers 3# @param target, a...
题目：用队列实现栈：使用队列实现栈的下列操作： push(x) -- 元素 x 入栈 pop() -- 移除栈顶元素 top() -- 获取栈顶元素 empty() -- 返回栈是否为空 。注意:你只能使用队列的基本操作-- 也就是 push to back, peek/pop from front, size, 和 is empty 这些操作是合法的。你所使用的语言也许不支持队列。 你可以使用 list 或者 deque（双端队列）来模拟一个队列 , 只要是标准的队列操作即可。你可以假设所有操作都是有效的（例如,...
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。示例 1:输入: 121输出: true示例 2:输入: -121输出: false解释: 从左向右读, 为 -121 。 从右向左读, 为 121- 。因此它不是一个回文数。示例 3:输入: 10输出: false解释: 从右向左读, 为 01 。因此它不是一个回文数。进阶:你能不将整数转为字符串来解决这个问题吗？这道题不用进阶解法的确是非常容易解答的，直接转成字符串，然后反转一...