大礼包

// Java Stream Solution
// 题目思路：
// 1. 与Java方法类似，使用stream和lambda表达式来简化代码逻辑。
// 2. 使用stream API遍历special大礼包，并计算所有可能的最低价格。
 
import java.util.*;
 
public class Solution {
    public int shoppingOffers(List<Integer> price, List<List<Integer>> special, List<Integer> needs) {
        return dfs(price, special, needs);
    }
 
    private int dfs(List<Integer> price, List<List<Integer>> special, List<Integer> needs) {
        int minPrice = needs.stream().mapToInt(i -> price.get(i) * needs.get(i)).sum();
        for (List<Integer> offer : special) {
            List<Integer> clone = new ArrayList<>(needs);
            boolean valid = true;
            for (int i = 0; i < needs.size(); i++) {
                int diff = clone.get(i) - offer.get(i);
                if (diff < 0) {
                    valid = false;
                    break;
                }
                clone.set(i, diff);
            }
            if (valid) {
                minPrice = Math.min(minPrice, offer.get(needs.size()) + dfs(price, special, clone));
            }
        }
        return minPrice;
    }
}