Write a function to find the longest common prefix string amongst an array of strings.

Write a function to find the longest common prefix string amongst an array of strings. If there is no common prefix, return an empty string “”. Example 1: Input: strs =

Roman to Integer

Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M. Symbol Value I 1 V 5 X 10 L 50 C 100 D 500 M 1000 For example, 2 is written as II in Roman numeral,

Integer to Roman

Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M. Symbol Value I 1 V 5 X 10 L 50 C 100 D 500 M 1000 For example, 2 is written as II in Roman numeral,

Regular Expression Matching

Given an input string s and a pattern p, implement regular expression matching with support for ‘.’ and ‘*’ where: ‘.’ Matches any single character.​​​​ ‘*’ Matches zero or more of the preceding element. The matching should cover the entire input

Palindrome Number without converting the integer to a string

Given an integer x, return true if x is palindrome integer. An integer is a palindrome when it reads the same backward as forward. For example, 121 is a palindrome while 123 is not. Example 1: Input: x = 121 Output:

Reverse Integer

Given a signed 32-bit integer x, return x with its digits reversed. If reversing x causes the value to go outside the signed 32-bit integer range [-231, 231 – 1], then return 0. Assume the environment does not

Zigzag Conversion

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

Longest Palindromic Substring

Given a string s, return the longest palindromic substring in s. Example 1: Input: s = “babad” Output: “bab” Explanation: “aba” is also a valid answer. Example 2: Input: s = “cbbd” Output: “bb”

Given a string s, find the length of the longest substring without repeating characters.

Example 1: Input: s = “abcabcbb” Output: 3 Explanation: The answer is “abc”, with the length of 3. Example 2: Input: s = “bbbbb” Output: 1 Explanation: The answer is

Given two sorted arrays nums1 and nums2 of size m and n respectively, return the median of the two sorted arrays.

The overall run time complexity should be O(log (m+n)). Example 1: Input: nums1 = [1,3], nums2 = [2] Output: 2.00000 Explanation: merged array = [1,2,3] and median is 2. Example 2:

Leetcode: Given an integer array nums and an integer val, remove all occurrences of val in nums in-place. The relative order of the elements may be changed.

Since it is impossible to change the length of the array in some languages, you must instead have the result be placed in the first part of the array nums. More formally, if

LeetCode : Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target.

Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target. You may assume that each input would have exactly one solution, and you may