Best Time to Buy and Sell Stock III.java

class Solution {
public int maxProfit(int[] prices) {
 if (prices == null || prices.length < 2) {
return 0;
}
int[] left = new int[prices.length];
int[] right = new int[prices.length];
// DP from left to right
left[0] = 0;
int min = prices[0];
for (int i = 1; i < prices.length; i++) {
min = Math.min(min, prices[i]);
left[i] = Math.max(left[i - 1], prices[i] - min);
}
right[prices.length - 1] = 0;
int max = prices[prices.length - 1];
for (int i = prices.length - 2; i >= 0; i--) {
max = Math.max(max, prices[i]);
right[i] = Math.max(right[i + 1], max - prices[i]);
}
int profit = 0;
for (int i = 0; i < prices.length; i++) {
profit = Math.max(profit, left[i] + right[i]);
}
return profit;
}
}