Yano_nankai的博客

题目描述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 v

题目描述Implement 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() – Get the front element.empty(

题目描述Note: This is an extension of House Robber.After robbing those houses on that street, the thief has found himself a new place for his thievery so that he will not get too much attention. This time,

题目描述There are a total of n courses you have to take, labeled from 0 to n - 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

题目描述Write an algorithm to determine if a number is “happy”.A happy number is a number defined by the following process: Starting with any positive integer, replace the number by the sum of the squares

题目描述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 ho

题目描述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.分析用递归，首先要判断输入的两

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

题目描述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.Fo

题目描述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 b

题目描述Given a list, rotate the list to the right by k places, where k is non-negative.For example: Given 1->2->3->4->5->NULL and k = 2, return 4->5->1->2->3->NULL.代码 public static ListNode rotateRig

题目描述The set [1,2,3,…,n] contains a total of n! unique permutations.By listing and labeling all of the permutations in order, We get the following sequence (ie, for n = 3):“123”“132”“213”“231”“312

题目描述Given an integer n, generate a square matrix filled with elements from 1 to n2 in spiral order.For example, Given n = 3,You should return the following matrix: [ [ 1, 2, 3 ], [ 8, 9, 4 ], [

题目描述Given a string s consists of upper/lower-case alphabets and empty space characters ’ ‘, return the length of last word in the string.If the last word does not exist, return 0.Note: A word is define

题目描述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.Determine if you

题目描述Given a matrix of m x n elements (m rows, n columns), return all elements of the matrix in spiral order.For example, Given the following matrix:[ [ 1, 2, 3 ], [ 4, 5, 6 ], [ 7, 8, 9 ] ]You

题目描述Find the contiguous subarray within an array (containing at least one number) which has the largest sum.For example, given the array [−2,1,−3,4,−1,2,1,−5,4], the contiguous subarray [4,−1,2,1] has

题目描述Implement pow(x, n).代码 public double myPow(double x, int n) { if (n < 0) { return 1/pow(x, -n); } else { return pow(x, n); } } private doub

题目描述You are given an n x n 2D matrix representing an image.Rotate the image by 90 degrees (clockwise).Follow up: Could you do this in-place?分析代码public static void rotate(int[][] matrix) { if (matri

题目描述Given a collection of numbers that might contain duplicates, return all possible unique permutations.For example, [1,1,2] have the following unique permutations: [1,1,2], [1,2,1], and [2,1,1].分析使

题目描述Given a collection of numbers, return all possible permutations.For example, [1,2,3] have the following permutations: [1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], and [3,2,1].分析代码 public List<

题目描述Given two numbers represented as strings, return multiplication of the numbers as a string.Note: The numbers can be arbitrarily large and are non-negative.分析代码1 public String multiply(String num

题目描述Given a collection of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T.Each number in C may only be used once in the combinatio

题目描述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

题目描述The count-and-say sequence is the sequence of integers beginning as follows: 1, 11, 21, 1211, 111221, …1 is read off as “one 1” or 11. 11 is read off as “two 1s” or 21. 21 is read off as “one 2,

题目描述Determine if a Sudoku is valid, according to: Sudoku Puzzles - The Rules.The Sudoku board could be partially filled, where empty cells are filled with the character ‘.’.Note: A valid Sudoku board

题目描述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.H

题目描述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 th

题目描述Implement next permutation, which rearranges numbers into the lexicographically next greater permutation of numbers.If such arrangement is not possible, it must rearrange it as the lowest possible

题目描述Divide two integers without using multiplication, division and mod operator.If it is overflow, return MAX_INT.代码 public int divide(int dividend, int divisor) { if (divisor == 0) {

题目描述Implement strStr().Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.代码

题目描述Given an array and a value, remove all instances of that value in place and return the new length.The order of elements can be changed. It doesn’t matter what you leave beyond the new length.代码

题目描述Given a sorted array, remove the duplicates in place such that each element appear only once and return the new length.Do not allocate extra space for another array, you must do this in place with

题目描述Given a linked list, swap every two adjacent nodes and return its head.For example, Given 1->2->3->4, you should return the list as 2->1->4->3.Your algorithm should use only constant space. You ma

题目描述Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.For example, given n = 3, a solution set is:“((()))”, “(()())”, “(())()”, “()(())”, “()()()”代码

题目描述Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.代码 public ListNode mergeTwoLists(ListNode l1, ListNod

题目描述Given a string containing just the characters ‘(‘, ‘)’, ‘{‘, ‘}’, ‘[‘ and ‘]’, determine if the input string is valid.The brackets must close in the correct order, “()” and “()[]{}” are all valid b

题目描述Given a linked list, remove the nth node from the end of list and return its head.For example,Given linked list: 1->2->3->4->5, and n = 2.After removing the second node from the end, the linked lis

题目描述Given an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + d = target? Find all unique quadruplets in the array which gives the sum of target.Note: Elements in a

题目描述Given a digit string, return all possible letter combinations that the number could represent.A mapping of digit to letters (just like on the telephone buttons) is given below.Input:Digit string “2