原题链接: https://oj.leetcode.com/problems/best-time-to-buy-and-sell-stock/

public int maxProfit(int[] prices) {
    if (prices == null || prices.length == 0) return 0;

    int local = 0;
    int global = 0;
    for (int i = 1, len = prices.length; i < len; i++) {
        local = Math.max(local + prices[i] - prices[i - 1], 0);
        global = Math.max(local, global);
    }

    return global;
}

// brute force (time limit exceed)
public int maxProfit(int[] prices) {
    if (prices == null || prices.length == 0) return 0;

    int maxProfit = 0;
    int localProfit = 0;
    for (int i = 0, len = prices.length; i < len - 1; i++) {
        int max = 0;
        for (int j = i + 1; j < len; j++) {
            if (prices[j] > max) max = prices[j];
        }

        localProfit = max - prices[i];
        if (localProfit > maxProfit) maxProfit = localProfit;
    }

    return maxProfit;
}