## leetcode Find K Pairs with Smallest Sums

### leetcode Find K Pairs with Smallest Sums

You are given two integer arrays nums1 and nums2 sorted in ascending order and an integer k.

Define a pair (u,v) which consists of one element from the first array and one element from the second array.

Find the k pairs (u1,v1),(u2,v2) …(uk,vk) with the smallest sums.

Example 1:

Example 2:

Example 3:

## leetcode Super Pow

### leetcode Super Pow

Your task is to calculate ab mod 1337 where a is a positive integer and b is an extremely large positive integer given in the form of an array.

Example1:

Example2:

## leetcode Sum of Two Integers

### leetcode Sum of Two Integers

Calculate the sum of two integers a and b, but you are not allowed to use the operator `+` and `-`.

Example:
Given a = 1 and b = 2, return 3.

## leetcode Largest Divisible Subset

### leetcode Largest Divisible Subset

Given a set of distinct positive integers, find the largest subset such that every pair (Si, Sj) of elements in this subset satisfies: Si % Sj = 0 or Sj% Si = 0.

If there are multiple solutions, return any subset is fine.

Example 1:

Example 2:

## leetcode Valid Perfect Square

### leetcode Valid Perfect Square

Given a positive integer num, write a function which returns True if num is a perfect square else False.

Note: Do not use any built-in library function such as `sqrt`.

Example 1:

Example 2:

## leetcode Water and Jug Problem

### leetcode Water and Jug Problem

You are given two jugs with capacities x and y litres. There is an infinite amount of water supply available. You need to determine whether it is possible to measure exactly z litres using these two jugs.

Operations allowed:

• Fill any of the jugs completely.
• Empty any of the jugs.
• Pour water from one jug into another till the other jug is completely full or the first jug itself is empty.

Example 1:

Example 2:

## leetcode Max Sum of Rectangle No Larger Than K

### leetcode Max Sum of Rectangle No Larger Than K

Given a non-empty 2D matrix matrix and an integer k, find the max sum of a rectangle in the matrix such that its sum is no larger than k.

Example:

The answer is `2`. Because the sum of rectangle `[[0, 1], [-2, 3]]` is 2 and 2 is the max number no larger than k (k = 2).

Note:

1. The rectangle inside the matrix must have an area > 0.
2. What if the number of rows is much larger than the number of columns?

## leetcode Count Numbers with Unique Digits

### leetcode Count Numbers with Unique Digits

Given a non-negative integer n, count all numbers with unique digits, x, where 0 ≤ x < 10n.

Example:
Given n = 2, return 91. (The answer should be the total numbers in the range of 0 ≤ x < 100, excluding `[11,22,33,44,55,66,77,88,99]`)

Design a simplified version of Twitter where users can post tweets, follow/unfollow another user and is able to see the 10 most recent tweets in the user’s news feed. Your design should support the following methods:

1. postTweet(userId, tweetId): Compose a new tweet.
2. getNewsFeed(userId): Retrieve the 10 most recent tweet ids in the user’s news feed. Each item in the news feed must be posted by users who the user followed or by the user herself. Tweets must be ordered from most recent to least recent.
3. follow(followerId, followeeId): Follower follows a followee.
4. unfollow(followerId, followeeId): Follower unfollows a followee.

Example:

## leetcode 169 Majority Element || leetcode 229 Majority Element II

### leetcode 169. Majority Element

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 always exist in the array.