Best Time to Buy and Sell Stock

问题描述

Say you have an array for which the ith element is the price of a given stock on day i.

If you were only permitted to complete at most one transaction (ie, buy one and sell one share of the stock), design an algorithm to find the maximum profit.

Example 1:

Input: [7, 1, 5, 3, 6, 4]
Output: 5
max. difference = 6-1 = 5 (not 7-1 = 6, as selling price needs to be larger than buying price)

Example 2:

Input: [7, 6, 4, 3, 1]
Output: 0
In this case, no transaction is done, i.e. max profit = 0.

题目链接

https://leetcode.com/problems/best-time-to-buy-and-sell-stock/description/

Python

DP的入门题目,先用模拟做

class Solution(object):
def maxProfit(self, prices):
"""
:type prices: List[int]
:rtype: int
"""
import sys
lowprice = sys.maxint
profit = 0
for price in prices:
if price < lowprice:
lowprice = price
if price - lowprice > profit:
profit = price -lowprice
return profit

Java

暴力求解

class Solution {
public int maxProfit(int[] prices) {
int max = 0;
int curMin = Integer.MAX_VALUE;
for (int i = 0; i < prices.length; i++) {
curMin = Math.min(curMin, prices[i]);
max = Math.max(max, prices[i] - curMin);
}
return max;
}
}

Golang

DP 求解

package main
import (
"fmt"
)
func MaxProfit(prices []int) int {
low := prices[0]
result := 0
for i := 1; i < len(prices); i++ {
if prices[i] < low {
low = prices[i]
}
if prices[i]-low > result {
result = prices[i] - low
}
}
return result
}
func main() {
a := []int{7, 3, 1, 2, 6, 8}
fmt.Println(MaxProfit(a[:]))
}