leetcode-go/easy/122.go

package main

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))
// }