20240814 Finished

src/problem/mod.rs

@@ -203,4 +203,5 @@ mod p64_minimum_path_sum;
 mod p63_unique_paths_ii;
 mod p97_interleaving_string;
 mod p72_edit_distance;
-mod p123_best_time_to_buy_and_sell_stock_iii;
+mod p123_best_time_to_buy_and_sell_stock_iii;
+mod p188_best_time_to_buy_and_sell_stock_iv;

src/problem/p188_best_time_to_buy_and_sell_stock_iv.rs

@@ -0,0 +1,42 @@
+/**
+ * [188] Best Time to Buy and Sell Stock IV
+ */
+pub struct Solution {}
+
+
+// submission codes start here
+
+impl Solution {
+    pub fn max_profit(k: i32, prices: Vec<i32>) -> i32 {
+        let n = prices.len();
+        let k = k as usize;
+
+        let mut dp = vec![(-prices[0], 0); k];
+
+        for i in 1..n {
+            for j in 0..k {
+                dp[j].0 = dp[j].0.max(if j == 0 {
+                    -prices[i]
+                } else {
+                    dp[j - 1].1 - prices[i]
+                });
+                dp[j].1 = dp[j].1.max(dp[j].0 + prices[i]);
+            }
+        }
+
+        dp[k - 1].1
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_188() {
+        assert_eq!(2, Solution::max_profit(2, vec![2, 4, 1]));
+        assert_eq!(7, Solution::max_profit(2, vec![3, 2, 6, 5, 0, 3]));
+    }
+}