leetcode-go/easy/122.go

package main

import (
	"fmt"
)

func maxProfitOld(prices []int) int {
	last, cost, profit := -1<<31, 1<<31-1, 0
	for _, v := range prices {
		if v < last {
			if last > cost {
				// sell stock
				profit += last - cost
				// buy stock
				cost = v
			}
		}
		if v < cost {
			// buy cheaper stock
			cost = v
		}
		// store price of yestoday
		last = v
	}
	// sell stock at last day
	if last > cost {
		profit += last - cost
	}
	return profit
}

// split into small pieces!
func maxProfit(prices []int) int {
	profit := 0
	for i := 1; i < len(prices); i++ {
		if prices[i] > prices[i-1] {
			profit += prices[i] - prices[i-1]
		}
	}
	return profit
}

func main() {
	a1 := []int{1, 2, 3, 46, 1, 4, 1, 4, 5}
	a2 := []int{2, 1}
	fmt.Println(maxProfit(a1))
	fmt.Println(maxProfit(a2))
}