Merge pull request #2159 from fwqaaq/patch-40

Update 0188.买卖股票的最佳时机IV.md about rust

problems/0188.买卖股票的最佳时机IV.md

@@ -474,6 +474,55 @@ function maxProfit(k: number, prices: number[]): number {
 };
 ```
 
+Rust：
+
+```rust
+impl Solution {
+    pub fn max_profit(k: i32, prices: Vec<i32>) -> i32 {
+        let mut dp = vec![vec![0; 2 * k as usize + 1]; prices.len()];
+
+        for v in dp[0].iter_mut().skip(1).step_by(2) {
+            *v = -prices[0];
+        }
+
+        for (i, &p) in prices.iter().enumerate().skip(1) {
+            for j in (0..2 * k as usize - 1).step_by(2) {
+                dp[i][j + 1] = dp[i - 1][j + 1].max(dp[i - 1][j] - p);
+                dp[i][j + 2] = dp[i - 1][j + 2].max(dp[i - 1][j + 1] + p);
+            }
+        }
+
+        dp[prices.len() - 1][2 * k as usize]
+    }
+}
+```
+
+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]
+    }
+}
+```
 
 
 <p align="center">