From 65531e6de8da4ed86347dc6b6980e9df0808d909 Mon Sep 17 00:00:00 2001
From: Jerry-306 <82520819+Jerry-306@users.noreply.github.com>
Date: Fri, 17 Sep 2021 10:11:52 +0800
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---
 ...�股票的最佳时机II（动态规划）.md | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/problems/0122.买卖股票的最佳时机II（动态规划）.md b/problems/0122.买卖股票的最佳时机II（动态规划）.md
index 5dfe3f0e..c324d392 100644
--- a/problems/0122.买卖股票的最佳时机II（动态规划）.md
+++ b/problems/0122.买卖股票的最佳时机II（动态规划）.md
@@ -202,6 +202,7 @@ Go：
 
 Javascript：
 ```javascript
+// 方法一：动态规划（dp 数组）
 const maxProfit = (prices) => {
     let dp = Array.from(Array(prices.length), () => Array(2).fill(0));
     // dp[i][0] 表示第i天持有股票所得现金。
@@ -222,6 +223,21 @@ const maxProfit = (prices) => {
 
     return dp[prices.length -1][0];
 };
+
+// 方法二：动态规划（滚动数组）
+const maxProfit = (prices) => {
+    // 滚动数组
+    // have: 第i天持有股票最大收益; notHave: 第i天不持有股票最大收益
+    let n = prices.length,
+        have = -prices[0],
+        notHave = 0;
+    for (let i = 1; i < n; i++) {
+        have = Math.max(have, notHave - prices[i]);
+        notHave = Math.max(notHave, have + prices[i]);
+    }
+    // 最终手里不持有股票才能保证收益最大化
+    return notHave;
+}
 ```