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 8cfb4c1b..fb1a6898 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
@@ -462,6 +462,33 @@ impl Solution {
 }
 ```
 
+空间优化：
+
+```rust
+impl Solution {
+    pub fn max_profit(k: i32, prices: Vec<i32>) -> i32 {
+        let mut dp = vec![0; 2 * k as usize + 1];
+        for v in dp.iter_mut().skip(1).step_by(2) {
+            *v = -prices[0];
+        }
+
+        for p in prices {
+            for i in 1..=2 * k as usize {
+                if i % 2 == 1 {
+                    // 买入
+                    dp[i] = dp[i].max(dp[i - 1] - p);
+                    continue;
+                }
+                // 卖出
+                dp[i] = dp[i].max(dp[i - 1] + p);
+            }
+        }
+
+        dp[2 * k as usize]
+    }
+}
+```
+
 
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