Question 34 : Stock Buy Sell to Maximize Profit

Given an array of integers representing stock price on single day, find max profit that can be earned by 1 transaction.

So you need to find pair (buyDay,sellDay) where buyDay < = sellDay and it should maximise the profit.
For example :

int arr[]={14, 12, 70, 15, 99, 65, 21, 90};
Max profit can be gain by buying at 1th day(0 based indexing) and sell at 4th day.
Max profit = 99-12 =87

Lets say we have array arr[] of stock prices.
We will track two variables :lowestPriceTillThatDayand maxProfit.

• lowestPriceTillThatDay will be initialise to arr[0].
• Iterate over stock price array arr[]
• If current element is greater than lowestPriceTillThatDay
  • calculate profit.
  • If profit is greater than maxProfit then update the maxProfit.
• If current element is lesser than lowestPriceTillThatDay
  • update lowestPriceTillThatDay with current element.
• We will get maxProfit in the end.

public static int calculateMaxProfit(int[] arr) {
        int lowestPriceTillThatDay = arr[0];
        int maxProfit = Integer.MIN_VALUE;
        for (int i = 0; i < arr.length; i++) {
            int profit = 0;
            if (arr[i] > lowestPriceTillThatDay) {
                profit = arr[i] - lowestPriceTillThatDay;
                if (profit > maxProfit) {
                    maxProfit = profit;
                }
            } else {
                lowestPriceTillThatDay = arr[i];
            }
        }
        return maxProfit;
    }

Java Program for Stock Buy Sell to Maximize Profit

public class StockBuySellMain {
 
    public static void main(String[] args) {
        int arr[] = { 14, 12, 70, 15, 99, 65, 21, 90 };
        System.out.println("Maximum profit :" + calculateMaxProfit(arr));
 
    }
 
    public static int calculateMaxProfit(int[] arr) {
        int lowestPriceTillThatDay = arr[0];
        int maxProfit = Integer.MIN_VALUE;
        for (int i = 0; i < arr.length; i++) {
            int profit = 0;
            if (arr[i] > lowestPriceTillThatDay) {
                profit = arr[i] - lowestPriceTillThatDay;
                if (profit > maxProfit) {
                    maxProfit = profit;
                }
            } else {
                lowestPriceTillThatDay = arr[i];
            }
        }
        return maxProfit;
    }
 
}

When you run above program, you will get below output:

Maximum profit :87

Don't miss the next article! 

 

Be the first to be notified when a new article or Kubernetes experiment is published.                            

   Share This

• Facebook
• Twitter
• Linkedin
• Pinteres