LeetCode - Best Time to Buy and Sell Stock

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

第一题很简单，时间复杂度为 O(N)