package main

import "fmt"

const INT_MAX = int(^uint(0) >> 1)

func main() {
    s := []int{7, 1, 5, 3, 6, 4}
    fmt.Println("双重遍历法：", MaxProfit2(s))
    fmt.Println("一次遍历法：", MaxProfit1(s))
}

//双重遍历法
func MaxProfit2(prices []int) int {
    maxprofit := 0
    for i := 0; i < len(prices); i++ {
        for j := i + 1; j < len(prices); j++ {
            profit := prices[j] - prices[i]
            if profit > maxprofit {
                maxprofit = profit
            }
        }
    }
    return maxprofit
}

//一次遍历法
func MaxProfit1(prices []int) int {
    minprice := INT_MAX
    maxprofit := 0
    for i := 0; i < len(prices); i++ {
        if prices[i] < minprice {
            minprice = prices[i]
        } else if prices[i]-minprice > maxprofit {
            maxprofit = prices[i] - minprice
        }
    }
    return maxprofit
}