Lu_gee的博客

题目描述： Given an array of integers, return indices of the two numbers such that they add up to a specific target.You may assume that each input would have exactly one solution, and you may not use the s

题目描述： Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).For example, this binary tree [1,2,2,3,4,4,3] is symmetric: 1 / \ 2 2 / \ / \3

题目描述： Given an array of strings, group anagrams together.For example, given: [“eat”, “tea”, “tan”, “ate”, “nat”, “bat”], Return:[ ["ate", "eat","tea"], ["nat","tan"], ["bat"]]Note: All inputs

题目描述： Given a binary tree, return the level order traversal of its nodes’ values. (ie, from left to right, level by level).For example: Given binary tree [3,9,20,null,null,15,7], 3 / \ 9

题目描述： Given a set of distinct integers, nums, return all possible subsets.Note: The solution set must not contain duplicate subsets.For example, If nums = [1,2,3], a solution is: [ [3], [1],

题目描述： Given n non-negative integers a1, a2, …, an, where each represents a point at coordinate (i, ai). n vertical lines are drawn such that the two endpoints of line i is at (i, ai) and (i, 0). Find

题目描述： Given a binary tree, flatten it to a linked list in-place.For example, Given 1 / \ 2 5 / \ \ 3 4 6The flattened tree should look like:1 \ 2 \ 3 \ 4

题目描述： 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

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

题目描述： Given a binary tree, determine if it is a valid binary search tree (BST).Assume a BST is defined as follows:The left subtree of a node contains only nodes with keys less than the node’s key. Th

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

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

题目描述： 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?Note: Given n will be a positi

题目描述：Given an array S of n integers, find three integers in S such that the sum is closest to a given number, target. Return the sum of the three integers. You may assume that each input would have exa

题目描述：Reverse digits of an integer.Example1: x = 123, return 321 Example2: x = -123, return -321Note: The input is assumed to be a 32-bit signed integer. Your function should return 0 when the reverse

题目描述： 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?AC代码：class Solution(object): def isPalindrome(self, head): """

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

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 a collection of intervals, merge all overlapping intervals.For example： Given [1,3],[2,6],[8,10],[15,18], return [1,6],[8,10],[15,18].AC代码：class Solution(object): def merge(self, int

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 th

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

题目描述： Given an array of integers sorted in ascending order, 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 ta

题目描述： Invert a binary tree. 4 / \ 2 7 / \ / \1 3 6 9to 4 / \ 7 2 / \ / \9 6 3 1思路： 运用递归前序遍历二叉树来实现交换AC代码：class Solution(object): def invertTree(self,