122.买卖股票的最佳时机Ⅱ

贪心

时间复杂度$O(n)$

空间复杂度$O(1)$

class Solution {
    public int maxProfit(int[] prices) {
        int ans = 0, pre = prices[0];
        for (int i = 1; i < prices.length; ++i) {
            int cur = prices[i];
            if (cur > pre) {
                ans += cur - pre;
            }
            pre = cur;
        }
        return ans;
    }
}