dyllanzhou的专栏

Given a string S and a string T, find the minimum window in S which will contain all the characters in T in complexity O(n).For example,S = "ADOBECODEBANC"T = "ABC"Minimum window is "BANC".

Design an algorithm to encode a list of strings to a string. The encoded string is then sent over the network and is decoded back to the original list of strings.Machine 1 (sender) has the functio

Given a non-empty binary search tree and a target value, find k values in the BST that are closest to the target.Note:Given target value is a floating point.You may assume k is always valid, t

There are a total of n courses you have to take, labeled from 0 ton - 1.Some courses may have prerequisites, for example to take course 0 you have to first take course 1, which is expressed as a p

Implement a basic calculator to evaluate a simple expression string.The expression string may contain open ( and closing parentheses ), the plus + or minus sign -, non-negative integers and empty

Given an integer array of size n, find all elements that appear more than⌊ n/3 ⌋ times. The algorithm should run in linear time and in O(1) space.class Solution {public: /*alorithm: hash solu

Given a non-empty binary search tree and a target value, find the value in the BST that is closest to the target.Note:Given target value is a floating point.You are guaranteed to have only one

Given a sorted integer array where the range of elements are [lower, upper] inclusive, return its missing ranges.For example, given [0, 1, 3, 50, 75], lower = 0 and upper = 99, return ["2", "4->49", "

Implement an iterator over a binary search tree (BST). Your iterator will be initialized with the root node of a BST.Calling next() will return the next smallest number in the BST.Note: next() and

All DNA is composed of a series of nucleotides abbreviated as A, C, G, and T, for example: "ACGAATTCCG". When studying DNA, it is sometimes useful to identify repeated sequences within the DNA.Write

Given a binary tree, return all root-to-leaf paths.For example, given the following binary tree: 1 / \2 3 \ 5All root-to-leaf paths are:["1->2->5", "1->3"]algorithm: dfs /*

There are a total of n courses you have to take, labeled from 0 ton - 1.Some courses may have prerequisites, for example to take course 0 you have to first take course 1, which is expressed as a p

algorithmKahn algorithmL ← Empty list that will contain the sorted elementsS ← Set of all nodes with no incoming edgeswhile S is non-empty do remove a node n from S add n to tail of L

Given a binary search tree (BST), find the lowest common ancestor (LCA) of two given nodes in the BST.According to the definition of LCA on Wikipedia: “The lowest common ancestor is defined betwee

Implement Queue using StacksImplement the following operations of a queue using stacks.push(x) -- Push element x to the back of queue.pop() -- Removes the element from in front of queue.peek()

Given a singly linked list, determine if it is a palindrome.Follow up:Could you do it in O(n) time and O(1) space?/**  * Definition for singly-linked list.  * struct ListNode {  *     int va

Given an array of n positive integers and a positive integer s, find the minimal length of a subarray of which the sum ≥ s. If there isn't one, return 0 instead.For example, given the array [2,3,1

Given a sorted integer array without duplicates, return the summary of its ranges.For example, given [0,1,2,4,5,7], return ["0->2","4->5","7"].class Solution {public: string itos(int num){

Rotate an array of n elements to the right by k steps.For example, with n = 7 and k = 3, the array [1,2,3,4,5,6,7] is rotated to[5,6,7,1,2,3,4]. Note:Try to come up as many solutions as you ca

Given an array of n integers where n > 1, nums, return an arrayoutput such that output[i] is equal to the product of all the elements ofnums except nums[i].Solve it without division and in O(n).

Given two integers representing the numerator and denominator of a fraction, return the fraction in string format.If the fractional part is repeating, enclose the repeating part in parentheses.For

Given a binary tree, find the lowest common ancestor (LCA) of two given nodes in the tree.According to the definition of LCA on Wikipedia: “The lowest common ancestor is defined between two nodes

Given a m x n grid filled with non-negative numbers, find a path from top left to bottom right whichminimizes the sum of all numbers along its path.Note: You can only move either down or right at

A peak element is an element that is greater than its neighbors.Given an input array where num[i] ≠ num[i+1], find a peak element and return its index.The array may contain multiple peaks, in that

Given a 2d grid map of '1's (land) and '0's (water), count the number of islands. An island is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. You may assume

Given an array where elements are sorted in ascending order, convert it to a height balanced BST./** * Definition for a binary tree node. * struct TreeNode { * int val; * TreeNode *left;

Given a linked list, determine if it has a cycle in it.Follow up:Can you solve it without using extra space?class Solution {public: /*algorithm: hash solution time O(n) space O(n)

There are a row of n houses, each house can be painted with one of the k colors. The cost of painting each house with a certain color is different. You have to paint all the houses such that no two ad

There are a row of n houses, each house can be painted with one of the three colors: red, blue or green. The cost of painting each house with a certain color is different. You have to paint all the ho

Given a binary tree struct TreeLinkNode { TreeLinkNode *left; TreeLinkNode *right; TreeLinkNode *next; }Populate each next pointer to point to its next right node. If the

Given a binary tree, return the inorder traversal of its nodes' values.For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3return [1,3,2].Note: Recursive solution is trivi

Suppose a sorted array is rotated at some pivot unknown to you beforehand.(i.e., 0 1 2 4 5 6 7 might become 4 5 6 7 0 1 2).Find the minimum element.You may assume no duplicate exists in the arra

Given an array of non-negative integers, you are initially positioned at the first index of the array.Each element in the array represents your maximum jump length at that position.Your goal is

Given an integer (signed 32 bits), write a function to check whether it is a power of 4.Example:Given num = 16, return true.Given num = 5, return false.Follow up: Could you solve it without loop

Given two arrays, write a function to compute their intersection.Example:Given nums1 = [1, 2, 2, 1], nums2 = [2, 2], return[2].Note:Each element in the result must be unique.The result c

Given a binary tree, return the preorder traversal of its nodes' values.For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3return [1,2,3].Note: Recursive solution is triv

Given n, how many structurally unique BST's (binary search trees) that store values 1...n?For example,Given n = 3, there are a total of 5 unique BST's. 1 3 3 2 1 \

Given a binary search tree, write a function kthSmallest to find thekth smallest element in it.Note: You may assume k is always valid, 1 ≤ k ≤ BST's total elements.Follow up:What if the BST

Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity./** * Definition for singly-linked list. * struct ListNode { * int val; * ListNode *next

Given an array of numbers, verify whether it is the correct preorder traversal sequence of a binary search tree.You may assume each number in the sequence is unique.Follow up:Could you do it