[LeetCode] Best Time to Buy and Sell Stock 買賣股票的最佳時間

 

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.

 

這道題相當簡單，感覺達不到Medium的難度，只需要遍歷一次數組，用一個變量記錄遍歷過數中的最小值，然后每次計算當前值和這個最小值之間的差值最為利潤，然后每次選較大的利潤來更新。當遍歷完成后當前利潤即為所求，代碼如下：

 

C++ 解法：

class Solution {
public:
    int maxProfit(vector<int>& prices) {
        int res = 0, buy = INT_MAX;
        for (int price : prices) {
            buy = min(buy, price);
            res = max(res, price - buy);
        }
        return res;
    }
};

 

Java 解法：

public class Solution {
    public int maxProfit(int[] prices) {
        int res = 0, buy = Integer.MAX_VALUE;
        for (int price : prices) {
            buy = Math.min(buy, price);
            res = Math.max(res, price - buy);
        }
        return res;
    }
}

 

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