121. Best Time to Buy and Sell Stock

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 class Solution {    public int maxProfit(int[] prices) {        if (prices.length<=1) {            return 0;        }        Integer[] mins = new Integer[prices.length]; // first n days        Integer[] maxs = new Integer[prices.length]; // last n days        mins[0] = prices[0];        maxs[prices.length-1] = prices[prices.length-1];        // fill max prices, from right to left        for (int i=prices.length-2; i>=0; i--) {            if (prices[i]>maxs[i+1])                maxs[i] = prices[i];            else                maxs[i] = maxs[i+1];        }        // fill min prices, and calculate the biggest profit, from left to right        int biggestProfit = 0;        for (int i=1; i<prices.length; i++) {            if (prices[i]<mins[i-1])                mins[i] = prices[i];            else                mins[i] = mins[i-1];            int profit = maxs[i] - mins[i];            if (profit>biggestProfit)                biggestProfit = profit;        }        return biggestProfit;    }}