iboxty的专栏

Find the contiguous subarray within an array (containing at least one number) which has the largest product.For example, given the array [2,3,-2,4], the contiguous subarray [2,3] has the largest produ

Given a binary tree, determine if it is height-balanced.For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node never differ by

Sort a linked list using insertion sort.正好复习一下插入排序，它时间复杂度是O(n^2).最优复杂度：当输入数组就是排好序的时候，复杂度为O(n) (快速排序在这种情况下会产生O(n^2)的复杂度)。 最差复杂度：当输入数组为倒序时，复杂度为O(n^2)它是一种In-place sort，不需要额外的空间消耗。 实现的算法如下： (http://b

Follow up for “Unique Paths”:Now consider if some obstacles are added to the grids. How many unique paths would there be?An obstacle and empty space is marked as 1 and 0 respectively in the grid.DP 有障

Given a binary tree, return the preorder traversal of its nodes’ values.For example: Given binary tree {1,#,2,3},1 \ 2 / 3树的前序遍历/** * Definition for binary tree * struct TreeNode

Given an integer n, return the number of trailing zeroes in n!.Note: Your solution should be in logarithmic time complexity.一开始就想1~n中统计被2整除和被5整除的因子有多少，取两个中较小的。但复杂度是O(nlgn)，不符合题目要求。class Solution {publ

Sort a linked list in O(n log n) time using constant space complexity.归并排序，找中点用快慢指针。/** * Definition for singly-linked list. * struct ListNode { * int val; * ListNode *next; * ListNode

Given numRows, generate the first numRows of Pascal’s triangle.For example, given numRows = 5, Return[ [1], [1,1], [1,2,1], [1,3,3,1], [1,4,6,4,1] ]class Solution {public: ve

Design a stack that supports push, pop, top, and retrieving the minimum element in constant time.push(x) – Push element x onto stack. pop() – Removes the element on top of the stack. top() – Get the

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 a

The demons had captured the princess (P) and imprisoned her in the bottom-right corner of a dungeon. The dungeon consists of M x N rooms laid out in a 2D grid. Our valiant knight (K) was initially posi

Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list.For example, Given 1->2->3->3->4->4->5, return 1->2->5. Given 1->1->1->2

Given a sorted linked list, delete all duplicates such that each element appear only once.For example, Given 1->1->2, return 1->2. Given 1->1->2->3->3, return 1->2->3.链表的简单应用，一开始没有加if(head==NULL) ret

Given a set of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T.The same repeated number may be chosen from C unlimited number of t

Given a set of distinct integers, S, return all possible subsets.Note: Elements in a subset must be in non-descending order. The solution set must not contain duplicate subsets. For example, If S =

Given two integers n and k, return all possible combinations of k numbers out of 1 … n.For example, If n = 4 and k = 2, a solution is:[ [2,4], [3,4], [2,3], [1,2], [1,3], [1,4], ]这道

Say you have an array for which the ith element is the price of a given stock on day i.If you were only permitted to complete at most one transaction (ie, buy one and sell one share of the stock), desi

Given a collection of integers that might contain duplicates, S, return all possible subsets.Note: Elements in a subset must be in non-descending order. The solution set must not contain duplicate su

Given a string s and a dictionary of words dict, add spaces in s to construct a sentence where each word is a valid dictionary word.Return all such possible sentences.For example, given s = “catsanddo

You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping you from robbing each of them is that adjacent houses

Given a 2D board and a word, find if the word exists in the grid.The word can be constructed from letters of sequentially adjacent cell, where “adjacent” cells are those horizontally or vertically neig

Given an array of integers, every element appears three times except for one. Find that single one.Note: Your algorithm should have a linear runtime complexity. Could you implement it without using ex

Given an array of integers, every element appears twice except for one. Find that single one.Note:Your algorithm should have a linear runtime complexity. Could you implement it without using e

Reverse bits of a given 32 bits unsigned integer.For example, given input 43261596 (represented in binary as 00000010100101000001111010011100), return 964176192 (represented in binary as 00111001011110

Related to question Excel Sheet Column TitleGiven a column title as appear in an Excel sheet, return its corresponding column number.class Solution {public: int titleToNumber(string s) { i

Given a binary tree, find its maximum depth.The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.DFS/** * Definition for binary tree * str

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

Given two binary trees, write a function to check if they are equal or not.Two binary trees are considered equal if they are structurally identical and the nodes have the same value./** * Definition f

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

Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).DFS 对称的比较每个节点的值/** * Definition for binary tree * struct TreeNode { * int val; * TreeNode *lef

A robot is located at the top-left corner of a m x n grid (marked ‘Start’ in the diagram below).The robot can only move either down or right at any point in time. The robot is trying to reach the botto

Given a triangle, find the minimum path sum from top to bottom. Each step you may move to adjacent numbers on the row below.貌似想的有点复杂了，第一行一定只有一个元素class Solution {public: int minimumTotal(vector<vec

Given an array of size n, find the majority element. The majority element is the element that appears more than ⌊ n/2 ⌋ times.You may assume that the array is non-empty and the majority element always

Write a function that takes an unsigned integer and returns the number of ’1’ bits it has (also known as the Hamming weight).For example, the 32-bit integer ’11’ has binary representation 0000000000000

Follow up for problem “Populating Next Right Pointers in Each Node”.What if the given tree could be any binary tree? Would your previous solution still work?Note:You may only use constant extra space

Given a binary tree, find its minimum depth.The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.DFS/** * Definition for binary tree * str

Two elements of a binary search tree (BST) are swapped by mistake.Recover the tree without changing its structure.Note: A solution using O(n) space is pretty straight forward. Could you devise a const

Given a positive integer, return its corresponding column title as appear in an Excel sheet.class Solution {public: string convertToTitle(int n) { if(n<1) return ""; string s,str;

Implement int sqrt(int x).Compute and return the square root of x.二分搜索class Solution {public: int sqrt(int x) { if(x==1||x==2||x==3) return 1; return binary(0,x,x); } int bi

You are climbing a stair case. It takes n steps to reach to the top.Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?DPclass Solution {public: int cl