Brooke

一、題目

Given an integer number n, return the difference between the product of its digits and the sum of its digits.

 

Example 1:

Input: n = 234 Output: 15 Explanation: Product of digits = 2 * 3 * 4 = 24 Sum of digits = 2 + 3 + 4 = 9 Result = 24 - 9 = 15

Example 2:

Input: n = 4421 Output: 21 Explanation: Product of digits = 4 * 4 * 2 * 1 = 32 Sum of digits = 4 + 4 + 2 + 1 = 11 Result = 32 - 11 = 21

 

Constraints:

• 1 <= n <= 10^5

 

二、程式作法

public class Solution
{
    public int SubtractProductAndSum(int n)
    {
        Queue<int> queue = new Queue<int>();

        while (n / 10 != 0)
        {
            queue.Enqueue(n % 10);
            n /= 10;
        }

        if (n != 0)
            queue.Enqueue(n);

        int p = 1, s = 0;

        while (queue.Count > 0)
        {
            int temp = queue.Dequeue();
            p *= temp;
            s += temp;
        }

        return p - s;
    }
}

 

public class Solution
{
    public int SubtractProductAndSum(int n)
    {
        int[] collection = new int[(int)Math.Log(n, 10) + 1];

        int idx = 0;
        while (n > 0)
        {
            collection[idx] = n % 10;
            idx++;
            n /= 10;
        }

        int p = 1;
        for (int i = 0; i < collection.Length; i++)
            p *= collection[i];

        int s = 0;
        for (int i = 0; i < collection.Length; i++)
            s += collection[i];

        return p - s;
    }
}

 

三、思路筆記

兩種作法，一種用 Queue 來分出每一個數字；

另一種是取 log 來分出每一種數字。