05.best time to buy and sell stocks.java

/*
You are given an array prices where prices[i] is the price of a given stock on the ith day.

You want to maximize your profit by choosing a single day to buy one stock and choosing a different day in the future to sell that stock.

Return the maximum profit you can achieve from this transaction. If you cannot achieve any profit, return 0.

 

Example 1:

Input: prices = [7,1,5,3,6,4]
Output: 5
Explanation: Buy on day 2 (price = 1) and sell on day 5 (price = 6), profit = 6-1 = 5.
Note that buying on day 2 and selling on day 1 is not allowed because you must buy before you sell.
Example 2:

Input: prices = [7,6,4,3,1]
Output: 0
Explanation: In this case, no transactions are done and the max profit = 0.
*/
class Solution {
    public int maxProfit(int[] prices){
        int min= Integer.MAX_VALUE;
    int profit=0;
    for(int i=0;i<prices.length;i++){
        if(prices[i]<min){
            min=prices[i];
        }
        else if(prices[i]-min>profit){
          profit=prices[i]-min;  
        }
        
    }
    return profit;
        
    }
}


//solution according to coding ninja
import java.util.* ;
import java.io.*; 
import java.util.ArrayList;

public class Solution{
    public static int maximumProfit(ArrayList<Integer> prices){
 int min= Integer.MAX_VALUE;
    int profit=0;
    for(int i=0;i<prices.size();i++){
        if(prices.get(i)<min){
            min=prices.get(i);
        }
        else if(prices.get(i)-min>profit){
          profit=prices.get(i)-min;  
        }
        
    }
    return profit;
    }
}