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Given an array of integers representing stock price on a single day, find max profit that can be earned by 1 transaction.
So you need to find a pair (buyDay,sellDay) where buyDay < = sellDay and it should maximize the profit. For example:
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int arr[]={14, 12, 70, 15, 99, 65, 21, 90}; Max profit can be gain by buying on 1st day(0 based indexing) and sell on the 4th day. Max profit = 99-12 =87 |
Stock Buy Sell to Maximize Profit Algorithm
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.
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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
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package org.arpit.java2blog; 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:
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Maximum profit :87 |
That’s all about Stock Buy Sell to Maximize Profit.
