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0123-best-time-to-buy-and-sell-stock-iii.rb
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# frozen_string_literal: true
# 123. Best Time to Buy and Sell Stock III
# https://leetcode.com/problems/best-time-to-buy-and-sell-stock-iii
# Hard
=begin
You are given an array prices where prices[i] is the price of a given stock on the ith day.
Find the maximum profit you can achieve. You may complete at most two transactions.
Note: You may not engage in multiple transactions simultaneously (i.e., you must sell the stock before you buy again).
Example 1:
Input: prices = [3,3,5,0,0,3,1,4]
Output: 6
Explanation: Buy on day 4 (price = 0) and sell on day 6 (price = 3), profit = 3-0 = 3.
Then buy on day 7 (price = 1) and sell on day 8 (price = 4), profit = 4-1 = 3.
Example 2:
Input: prices = [1,2,3,4,5]
Output: 4
Explanation: Buy on day 1 (price = 1) and sell on day 5 (price = 5), profit = 5-1 = 4.
Note that you cannot buy on day 1, buy on day 2 and sell them later, as you are engaging multiple transactions at the same time. You must sell before buying again.
Example 3:
Input: prices = [7,6,4,3,1]
Output: 0
Explanation: In this case, no transaction is done, i.e. max profit = 0.
Constraints:
1 <= prices.length <= 105
0 <= prices[i] <= 105
=end
# @param {Integer[]} prices
# @return {Integer}
def max_profit(prices)
cost1 = cost2 = 100000
profit1 = profit2 = temp = 0
prices.each do |price|
cost1 = price if cost1 > price
profit1 = temp if profit1 < temp = price - cost1
cost2 = temp if cost2 > temp = price - profit1
profit2 = temp if profit2 < temp = price - cost2
end
profit2
end
# **************** #
# TEST #
# **************** #
require "test/unit"
class Test_max_profit < Test::Unit::TestCase
def test_
assert_equal 6, max_profit([3, 3, 5, 0, 0, 3, 1, 4])
assert_equal 4, max_profit([1, 2, 3, 4, 5])
assert_equal 0, max_profit([7, 6, 4, 3, 1])
end
end