## leetcode Guess Number Higher or Lower II

We are playing the Guess Game. The game is as follows:

I pick a number from

1ton. 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:

123456789 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 pay $7.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 + $7 + $9 = $21.Given a particular

n ≥ 1, find out how much money you need to have to guarantee awin.

Hint:

- The best strategy to play the game is to minimize the maximum loss you could possibly face. Another strategy is to minimize the expected loss. Here, we are interested in the
firstscenario.- Take a small example (n = 3). What do you end up paying in the worst case?
- Check out this article if you’re still stuck.
- The purely recursive implementation of minimax would be worthless for even a small n. You MUST use dynamic programming.
- As a follow-up, how would you modify your code to solve the problem of minimizing the expected loss, instead of the worst-case loss?

# dynamic programming

## leetcode Coin Change

## leetcode Coin Change

You are given coins of different denominations and a total amount of money

amount. Write a function to compute the fewest number of coins that you need to make up that amount. If that amount of money cannot be made up by any combination of the coins, return`-1`

.

Example 1:

coins =`[1, 2, 5]`

, amount =`11`

return`3`

(11 = 5 + 5 + 1)

Example 2:

coins =`[2]`

, amount =`3`

return`-1`

.

Note:

You may assume that you have an infinite number of each kind of coin.

## leetcode Best Time to Buy and Sell Stock with Cooldown

## leetcode Best Time to Buy and Sell Stock with Cooldown

Say you have an array for which the

i^{th}element is the price of a given stock on dayi.Design an algorithm to find the maximum profit. You may complete as many transactions as you like (ie, buy one and sell one share of the stock multiple times) with the following restrictions:

- You may not engage in multiple transactions at the same time (ie, you must sell the stock before you buy again).
- After you sell your stock, you cannot buy stock on next day. (ie, cooldown 1 day)

Example:prices = [1, 2, 3, 0, 2]

maxProfit = 3

transactions = [buy, sell, cooldown, buy, sell]

## leetcode Best Time to Buy and Sell Stock

本次题解包括

**121**Best Time to Buy and Sell Stock**122**Best Time to Buy and Sell Stock II**123**Best Time to Buy and Sell Stock III**188**Best Time to Buy and Sell Stock IV**714**. Best Time to Buy and Sell Stock with Transaction Fee