# LeetCode 416. Partition Equal Subset Sum

Given a non-empty array containing only positive integers, find if the array can be partitioned into two subsets such that the sum of elements in both subsets is equal.

# LeetCode 377. Combination Sum IV

Given an integer array with all positive numbers and no duplicates, find the number of possible combinations that add up to a positive integer target.

# LeetCode 376. Wiggle Subsequence

Description
A sequence of numbers is called a wiggle sequence if the differences between successive numbers strictly alternate between positive and negative. The first difference (if one exists) may be either positive or negative. A sequence with fewer than two elements is trivially a wiggle sequence.

LD 是个众所周知的糕富帅，从不把买切糕的钱当钱，只求量和品质，不惜价。但他还是会纠结买哪些切糕好，现假设切糕的价钱有 5 种分别为每两 2，2.5，3，3.5，4（百RMB），并且数量都假设为无限。现在告诉你 LD 一共有几百 RMB。请你告诉 LD 他一共有几种买切糕的方案（钱可以不花光，但一定要买，不花钱 LD 会不开心的）。

# LeetCode 375. Guess Number Higher or Lower II

Description
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 I picked is higher or lower.

However, when you guess a particular number x, and you guess wrong, you pay \$x. You win the game when you guess the number I picked.

Example:

n = 10, I pick 8.

First round: You guess 5, I tell you that it’s higher. You pay 5. Second round: You guess 7, I tell you that it’s higher. You pay5.Secondround:Youguess7,Itellyouthatit

shigher.Youpay7.
Third round: You guess 9, I tell you that it’s lower. You pay \$9.

Game over. 8 is the number I picked.

You end up paying 5 +5+7 + 9 =9=21.
Given a particular n ≥ 1, find out how much money you need to have to guarantee a win.

# LeetCode 368. Largest Divisible Subset

Description
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.

# LeetCode 363. Max Sum of Rectangle No Larger Than K

Description
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:

Input: matrix = [[1,0,1],[0,-2,3]], k = 2
Output: 2
Explanation: Because the sum of rectangle [[0, 1], [-2, 3]] is 2,
and 2 is the max number no larger than k (k = 2).
Note:

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