LC.P2240[买钢笔和铅笔的方案数]

方法一：枚举

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class Solution {
    public long waysToBuyPensPencils(int total, int cost1, int cost2) {
        long ans = 0;
        for (int x = 0; x <= total / cost1; ++x) {
            int y = (total - x * cost1) / cost2 + 1;
            ans += y;
        }
        return ans;
    }
}
  • 时间复杂度：$O(total/cost1)$
  • 空间复杂度：$O(1)$