Best Time to Buy and Sell Stock

public class Solution {

	/**
	 * 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.
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		int [] A = {2,1,4};
		System.out.print(new Solution().maxProfit(A));

	}
	public int maxProfit(int[] prices) {
        // Start typing your Java solution below
        // DO NOT write main() function
		
		if(prices == null || prices.length == 0)
			return 0;
		
		int maxprofit = 0;
		int lowest_before = Integer.MAX_VALUE;
		
		for(int i = 0; i < prices.length; i++){
			if(lowest_before > prices[i])
				lowest_before = prices[i];
			else if(prices[i] - lowest_before > maxprofit){
				maxprofit = prices[i] - lowest_before;
			}
			
		}		
		return maxprofit;        
    }
}