买钢笔和铅笔的方案数

/*
 * Problem: Same as above.
 *
 * Approach using Java Streams:
 * 1. We use IntStream to generate the number of pens we can buy.
 * 2. For each number of pens, calculate the remaining money and determine the number of pencils that can be bought.
 * 3. Sum up all the combinations using the sum method of the IntStream.
 */

import java.util.stream.IntStream;

public class Solution {
    public int waysToBuyPensPencils(int total, int cost1, int cost2) {
        return IntStream.rangeClosed(0, total / cost1)
                .map(pens -> (total - pens * cost1) / cost2 + 1)
                .sum();
    }
}