方法思路

1. 我们需要在有限预算内买尽可能多的物品
2. 贪心策略：优先购买价格低的物品，这样能买更多件
3. 考虑折扣：支持优惠的物品实际价格为原价的95%
4. 计算每个物品的实际价格，然后按价格从小到大排序
5. 从最便宜的物品开始购买，直到预算用完

代码实现

Java

import java.io.*;
import java.util.*;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String[] line = br.readLine().split(" ");
        int n = Integer.parseInt(line[0]);
        long k = Long.parseLong(line[1]);
        
        line = br.readLine().split(" ");
        int[] prices = new int[n];
        for (int i = 0; i < n; i++) {
            prices[i] = Integer.parseInt(line[i]);
        }
        
        String discounts = br.readLine();
        
        // 创建价格数组，不需要额外对象
        long[] actualPrices = new long[n];
        for (int i = 0; i < n; i++) {
            actualPrices[i] = discounts.charAt(i) == '1' ? 
                              prices[i] * 95L : prices[i] * 100L;
        }
        
        // 直接排序价格数组
        Arrays.sort(actualPrices);
        
        int count = 0;
        long totalCost = 0;
        k *= 100; // 将k也乘以100
        
        for (long price : actualPrices) {
            if (totalCost + price <= k) {
                totalCost += price;
                count++;
            } else {
                break;
            }
        }
        
        System.out.println(count);
    }
}

Python

def max_items(n, k, prices, discounts):
    # 计算实际价格
    actual_prices = []
    for i in range(n):
        if discounts[i] == '1':  # 支持优惠
            actual_prices.append(prices[i] * 0.95)
        else:
            actual_prices.append(prices[i])
    
    # 按实际价格排序
    items = sorted([(actual_prices[i], i) for i in range(n)])
    
    count = 0
    total_cost = 0
    
    for price, _ in items:
        if total_cost + price <= k:
            total_cost += price
            count += 1
        else:
            break
    
    return count
    
n, k = map(int, input().split())
prices = list(map(int, input().split()))
discounts = input()

print(max_items(n, k, prices, discounts))

C++

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int main() {
    int n, k;
    cin >> n >> k;
    
    vector<int> prices(n);
    for (int i = 0; i < n; i++) {
        cin >> prices[i];
    }
    
    string discounts;
    cin >> discounts;
    
    // 计算实际价格并排序
    vector<double> actual_prices;
    for (int i = 0; i < n; i++) {
        double price = discounts[i] == '1' ? prices[i] * 0.95 : prices[i];
        actual_prices.push_back(price);
    }
    
    sort(actual_prices.begin(), actual_prices.end());
    
    int count = 0;
    double total_cost = 0;
    
    for (double price : actual_prices) {
        if (total_cost + price <= k) {
            total_cost += price;
            count++;
        } else {
            break;
        }
    }
    
    cout << count << endl;
    return 0;
}