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Given two strings s and t which consist of only lowercase letters.String t is generated by random shuffling string s and then add one more letter at a random position.Find the letter that was

Given
 an 
arbitrary
 ransom
 note
 string 
and 
another 
string 
containing 
letters from
 all 
the 
magazines,
 write 
a 
function 
that 
will 
return 
true 
if 
the 
ransom 
 note 
can 
be 
constru

public class Solution { public int titleToNumber(String s) { int len=s.length(); int sum=0; int x=1; len--; while(len>=0){ sum+=(s.charAt(len)-6

Given two strings s and t, write a function to determine if t is an anagram of s.For example,s = "anagram", t = "nagaram", return true.s = "rat", t = "car", return false.Note:You may a

Write a program to check whether a given number is an ugly number.Ugly numbers are positive numbers whose prime factors only include 2, 3, 5. For example, 6, 8 are ugly while 14 is not ugly sinc

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

Write a function that takes a string as input and reverse only the vowels of a string.Example 1:Given s = "hello", return "holle".Example 2:Given s = "leetcode", return "leotcede".Note

Find the nth digit of the infinite integer sequence 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, ...Note:n is positive and will fit within the range of a 32-bit signed integer (n 31).Example 1:Input

Given an integer, write a function to determine if it is a power of two.My solution:public class Solution { public boolean isPowerOfTwo(int n) { if(n<1) return false;

Given a string, find the first non-repeating character in it and return it's index. If it doesn't exist, return -1.Examples:s = "leetcode"return 0.s = "loveleetcode",return 2.Note: 

397. Integer Replacement QuestionEditorial Solution My SubmissionsTotal Accepted: 7473Total Submissions: 26784Difficulty: MediumContributors: AdminGiven a positive

415. Add Strings QuestionEditorial Solution My SubmissionsTotal Accepted: 4311Total Submissions: 9894Difficulty: EasyContributors: AdminGiven two non-negative numbe

Given two binary strings, return their sum (also a binary string).For example,a = "11"b = "1"Return "100".public class Solution { public String addBinary(String a, String b) {

he 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 "

Implement strStr().Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.public class Solution { public int strStr(String haystack, Str

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

Write a function to find the longest common prefix string amongst an array of strings.My solution:public class Solution { public String longestCommonPrefix(String[] strs) { StringB

Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.For example,"A man, a plan, a canal: Panama" is a palindrome."race a car" is not a

Implement pow(x, n).My solution:public class Solution { public double myPow(double x, int n) { long l=(long)n; if(l>=0) return pow(x,l); else

Given a string s and a string t, check if s is subsequence of t.You may assume that there is only lower case English letters in both s and t. t is potentially a very long (length ~= 500,000) strin

Given a string, find the length of the longest substring without repeating characters.Examples:Given "abcabcbb", the answer is "abc", which the length is 3.Given "bbbbb", the answer is "b",

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?My Solutionpublic class

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

Given an input string, reverse the string word by word.For example,Given s = "the sky is blue",return "blue is sky the".My Solution:public class Solution { public String reverseWords

You have a total of n coins that you want to form in a staircase shape, where every k-th row must have exactly k coins.Given n, find the total number of full staircase rows that can be formed.

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.Wri

You 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 it as a link

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.Example:Given nums =

The string "PAYPALISHIRING" is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font for better legibility)P A H NA P L S I

Given an unsorted array, find the maximum difference between the successive elements in its sorted form.Try to solve it in linear time/space.Return 0 if the array contains less than 2 elements

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 va

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].public class Solution { public void rotat

Description:Count the number of prime numbers less than a non-negative number, n.public class Solution { public int countPrimes(int n) { boolean[] hash=new boolean[n]; int

We are playing the Guess Game. The game is as follows:I pick a number from 1 to n. You have to guess which number I picked.Every time you guess wrong, I'll tell you whether the number is h

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

Follow up for "Remove Duplicates":What if duplicates are allowed at most twice?For example,Given sorted array nums = [1,1,1,2,2,3],Your function should return length = 5, with the first fi

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->3.1.public class Soluti

The Hamming distance between two integers is the number of positions at which the corresponding bits are different.Given two integers x and y, calculate the Hamming distance.Note:0 ≤ x, y <

Given an array of integers where 1 ≤ a[i] ≤ n (n = size of array), some elements appear twice and others appear once.Find all the elements of [1, n] inclusive that do not appear in this array.Coul

Given two sorted integer arrays nums1 and nums2, merge nums2 into nums1 as one sorted array.Note:You may assume that nums1 has enough space (size that is greater or equal to m + n) to hold additional