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leetcode 121. best time to buy and sell stock

admin 11月 12, 2020 0

算法
Java
Leetcode
Golang

Question

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.
See it on Leetcode

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.

Hint

Brute force approach may result in Time Limit Exceeded. Try greedy approach.

Solution in Java and Golang

java
go

public class  {
    public int maxProfit(int[] prices) {
        int minPrice = Integer.MAX_VALUE;
        int maxProfit = 0;
        for (int i : prices) {
            if (i < minPrice) {
                minPrice = i;
            } else if (i - minPrice > maxProfit) {
                maxProfit = i - minPrice;
            }
        }
        return maxProfit;
    }
}