From 2e9902e32119430c80303cf8d9eabd484e30ec4e Mon Sep 17 00:00:00 2001
From: jackfiled <xcrenchangjun@outlook.com>
Date: Sun, 3 Nov 2024 15:05:30 +0800
Subject: [PATCH] 20241103 finished.

---
 src/problem/mod.rs                  |  2 +
 src/problem/p638_shopping_offers.rs | 94 +++++++++++++++++++++++++++++
 2 files changed, 96 insertions(+)
 create mode 100644 src/problem/p638_shopping_offers.rs

diff --git a/src/problem/mod.rs b/src/problem/mod.rs
index eb01e88..2e65742 100644
--- a/src/problem/mod.rs
+++ b/src/problem/mod.rs
@@ -292,3 +292,5 @@ mod p3165_maximum_sum_of_subsequence_with_non_adjacent_elements;
 mod p3259_maximum_energy_boost_from_two_drinks;
 
 mod p3226_number_of_bit_changes_to_make_two_integers_equal;
+
+mod p638_shopping_offers;
diff --git a/src/problem/p638_shopping_offers.rs b/src/problem/p638_shopping_offers.rs
new file mode 100644
index 0000000..877e127
--- /dev/null
+++ b/src/problem/p638_shopping_offers.rs
@@ -0,0 +1,94 @@
+/**
+ * [638] Shopping Offers
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::collections::HashMap;
+
+impl Solution {
+    pub fn shopping_offers(price: Vec<i32>, special: Vec<Vec<i32>>, needs: Vec<i32>) -> i32 {
+        let n = price.len();
+
+        // 过滤出有优惠的大礼包
+        let special: Vec<Vec<i32>> = special
+            .into_iter()
+            .filter_map(|s| {
+                (price
+                    .iter()
+                    .enumerate()
+                    .map(|(i, v)| s[i] * *v)
+                    .sum::<i32>()
+                    > s[n])
+                    .then_some(s)
+            })
+            .collect();
+
+        let mut memory = HashMap::new();
+
+        Self::dfs(&price, &special, needs, &mut memory)
+    }
+
+    fn dfs(
+        price: &Vec<i32>,
+        special: &Vec<Vec<i32>>,
+        current_needs: Vec<i32>,
+        memory: &mut HashMap<Vec<i32>, i32>,
+    ) -> i32 {
+        if let Some(&v) = memory.get(&current_needs) {
+            return v;
+        }
+
+        let n = price.len();
+        let mut min_price: i32 = current_needs
+            .iter()
+            .enumerate()
+            .map(|(i, &v)| price[i] * v)
+            .sum();
+
+        for s in special.iter() {
+            let special_price = s[n];
+
+            let mut next_need = Vec::with_capacity(n);
+            for (i, &v) in current_needs.iter().enumerate() {
+                if s[i] > v {
+                    break;
+                }
+
+                next_need.push(v - s[i]);
+            }
+
+            // 可以购买大礼包
+            if next_need.len() == n {
+                min_price =
+                    min_price.min(Self::dfs(price, special, next_need, memory) + special_price);
+            }
+        }
+
+        memory.insert(current_needs, min_price);
+        min_price
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_638() {
+        assert_eq!(
+            14,
+            Solution::shopping_offers(vec![2, 5], vec![vec![3, 0, 5], vec![1, 2, 10]], vec![3, 2])
+        );
+        assert_eq!(
+            11,
+            Solution::shopping_offers(
+                vec![2, 3, 4],
+                vec![vec![1, 1, 0, 4], vec![2, 2, 1, 9]],
+                vec![1, 2, 1]
+            )
+        );
+    }
+}