Tingmei的专栏

Problem: 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,#,#,15,7}, 3 /

Problem:Given a binary tree, return the zigzag level order traversal of its nodes' values. (ie, from left to right, then right to left for the next level and alternate between).For example:

ProblemGiven an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives the sum of zero.Note:Elements

Problem: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

Problem: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.

Problem: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:"((()))", "(()())", "(())

Problem:Given an array of integers, find two numbers such that they add up to a specific target number.The function twoSum should return indices of the two numbers such that they add up to t

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.两个有序单链表合并。/** * Definition for singly-linked list. *

Problem: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.两个有序数组合并。class Solution {public: void

Problem: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 f

Problem: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./**

Problem: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 th

Question: 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?递归求解。f(1) =

ProblemYou are given two linked lists representing two non-negative numbers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return

ProblemGiven two binary strings, return their sum (also a binary string).For example,a = "11"b = "1"Return "100".即模拟加法运算。class Solution {public: string addBinary(string a, str

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 sol

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.c

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

Problem:Given a binary tree, find its depth (maximum height).递归求解。/** * Definition for binary tree * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; *

Problem:Write a function to find the longest common prefix string amongst an array of strings.求所有字符串的最长公共前缀。class Solution {public: string longestCommonPrefix(vector &strs) { // S

Given an array of strings, return all groups of strings that are anagrams.Note: All inputs will be in lower-case.求数组中所有的anagramsclass Solution {public: vector anagrams(vector &strs) {

Problem:Given a binary tree, return the bottom-up level order traversal of its nodes' values. (ie, from left to right, level by level from leaf to root).For example:Given binary tree {3,

Problem: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

Problem: Implement pow(x, n).注意负数转化为整数时，可能会有溢出。class Solution {public: double pow(double x, int n) { // Start typing your C/C++ solution below // DO NOT write int main() funct

Problem:Given a number represented as an array of digits, plus one to the number.class Solution {public: vector plusOne(vector &digits) { // Start typing your C/C++ solution below

Problem:Implement strStr().Returns a pointer to the first occurrence of needle in haystack, or null if needle is not part of haystack.KMP字符串匹配算法。class Solution {public: char *strS

Problem: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.

Problem:Given a binary tree, determine if it is height-balanced.An example of a height-balanced tree. A height-balanced tree is a tree whose subtrees differ in height by no more than one

Problem: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 o

Problem:Given an unsorted integer array, find the first missing positive integer.For example,Given [1,2,0] return 3,and [3,4,-1,1] return 2.Your algorithm should run in O(n) time a

Problem: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./** * Definition

Problem:Implement int sqrt(int x).Compute and return the square root of x.牛顿迭代法。class Solution {public: int sqrt(int x) { // Start typing your C/C++ solution below

Problem:Given an array where elements are sorted in ascending order, convert it to a height balanced BST.For example,Given array [9,12,14,17,19,23,50,54,67,72,76],the below BST is one po

Implement atoi to convert a string to an integer.Hint: Carefully consider all possible input cases. If you want a challenge, please do not see below and ask yourself what are the possible inpu

Problem:Given an array with n objects colored red, white or blue, sort them so that objects of the same color are adjacent, with the colors in the order red, white and blue.Here, we will u

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,

Given inorder and postorder traversal of a tree, construct the binary tree.Note:You may assume that duplicates do not exist in the tree./** * Definition for binary tree * struct TreeNode {

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 yo

Given a string containing just the characters '(' and ')', find the length of the longest valid (well-formed) parentheses substring.For "(()", the longest valid parentheses substring is "()",

Merge k sorted linked lists and return it as one sorted list. Analyze and describe its complexity.时间复杂度为O(k*n)，其中n为lists的最大长度，/** * Definition for singly-linked list. * struct ListNode { *