Leetcode Best Time to Buy and Sell Stock III

Best Time to Buy and Sell Stock III Nov 7 '12
Say you have an array for which the ith element is the price of a given stock on day i.

Design an algorithm to find the maximum profit. You may complete at most two transactions.

Note:
You may not engage in multiple transactions at the same time (ie, you must sell the stock before you buy again).

Leetcode Best Time to Buy and Sell Stock III.java

public class Solution {
    public int maxProfit(int[] prices) {
        // Start typing your Java solution below
        // DO NOT write main() function
        if(prices == null || prices.length < 2) return 0;
        
        int minLR = prices[0];
        int maxRL = prices[prices.length - 1];
        int[] dpLR = new int[prices.length];
        int[] dpRL = new int[prices.length];
        int max = 0;
        
        for(int i = 1; i < prices.length; i++){
            if(prices[i] < minLR) minLR = prices[i];
            dpLR[i] = Math.max(dpLR[i - 1], prices[i] - minLR);
        }
        
        for(int i = prices.length - 2; i > -1; i--){
            if(prices[i] > maxRL) maxRL = prices[i];
            dpRL[i] = Math.max(dpRL[i + 1], maxRL - prices[i]);
        }
        
        for(int i = 0; i < prices.length; i++){
            max = Math.max(max, dpLR[i] + dpRL[i]);
        }
        
        return max;
    }
}