[leetCode]剑指 Offer 63. 股票的最大利润

解法

使用一个变量min保存数组前i-1个元素的最小值，扫描整个数组更新最小值的同时计算差值，通过打擂的方式获得最大利润。

class Solution {
    public int maxProfit(int[] prices) {
        if (prices == null || prices.length < 2) return 0;
        int min = prices[0];
        int maxDiff = prices[1] - min;
        for (int i = 2; i < prices.length; i++) {
            if (prices[i-1] < min)
                min = prices[i-1];
            int currentDiff = prices[i] - min;
            if (currentDiff > maxDiff)
                maxDiff = currentDiff;
        }
        return maxDiff < 0 ? 0 : maxDiff;
    }
}