From f38dc8aedc147c824b5eaa3621f399a623e9b681 Mon Sep 17 00:00:00 2001
From: feobay <feobay1@gmail.com>
Date: Fri, 30 Aug 2024 16:19:40 +0800
Subject: [PATCH] =?UTF-8?q?=E6=B7=BB=E5=8A=A00188.=E4=B9=B0=E5=8D=96?=
 =?UTF-8?q?=E8=82=A1=E7=A5=A8=E7=9A=84=E6=9C=80=E4=BD=B3=E6=97=B6=E6=9C=BA?=
 =?UTF-8?q?IVGo=E7=89=88=E6=9C=AC=E7=A9=BA=E9=97=B4=E4=BC=98=E5=8C=96?=
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---
 .../0188.买卖股票的最佳时机IV.md     | 42 +++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/problems/0188.买卖股票的最佳时机IV.md b/problems/0188.买卖股票的最佳时机IV.md
index def69277..0b1622ac 100644
--- a/problems/0188.买卖股票的最佳时机IV.md
+++ b/problems/0188.买卖股票的最佳时机IV.md
@@ -404,6 +404,47 @@ func max188(a, b int) int {
 }
 ```
 
+版本三：空间优化版本
+
+```go
+func maxProfit(k int, prices []int) int {
+    n := len(prices)
+    // k次交易，2 * k种状态
+    // 状态从1开始计算，避免判断
+    // 奇数时持有(保持或买入)
+    // 偶数时不持有(保持或卖出)
+    dp := make([][]int, 2)
+    dp[0] = make([]int, k * 2 + 1)
+    dp[1] = make([]int, k * 2 + 1)
+
+    // 奇数状态时持有，i += 2
+    for i := 1; i <= k * 2; i += 2 {
+        dp[0][i] = -prices[0]
+    }
+
+    for i := 1; i < len(prices); i++ {
+        for j := 1; j <= k * 2; j++ {
+            if j % 2 == 1 {
+                dp[i % 2][j] = max(dp[(i - 1) % 2][j], dp[(i - 1) % 2][j - 1] - prices[i])
+            } else {
+                dp[i % 2][j] = max(dp[(i - 1) % 2][j], dp[(i - 1) % 2][j - 1] + prices[i])
+            }
+        }
+    }
+
+    return dp[(n - 1) % 2][k * 2]
+}
+
+func max(a, b int) int {
+    if a > b {
+        return a
+    }
+    return b
+}
+```
+
+
+
 ### JavaScript:
 
 ```javascript
@@ -558,3 +599,4 @@ impl Solution {
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
+