https://github.com/yuanyu90221/subtract-the-product-and-sum-of-digits-of-an-integer

https://github.com/yuanyu90221/subtract-the-product-and-sum-of-digits-of-an-integer

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• Host: GitHub
• URL: https://github.com/yuanyu90221/subtract-the-product-and-sum-of-digits-of-an-integer
• Owner: yuanyu90221
• Created: 2020-08-12T15:52:21.000Z (over 4 years ago)
• Default Branch: master
• Last Pushed: 2020-08-12T15:58:39.000Z (over 4 years ago)
• Last Synced: 2024-04-21T14:01:26.461Z (9 months ago)
• Language: Go
• Size: 1.95 KB
• Stars: 0
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# subtract-the-product-and-sum-of-digits-of-an-integer

## 題目解讀：

### 題目來源:

[subtract-the-product-and-sum-of-digits-of-an-integer](https://leetcode.com/problems/subtract-the-product-and-sum-of-digits-of-an-integer/)

### 原文:

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

### 解讀：

給定一個正整數 n

回傳 n的每個digit相乘 減去 n的每個digit相加的結果

舉例來說:

n = 234

f(n) => 2 * 3 * 4 - 2+3+4= 24 - 9 =15

## 初步解法:

### 初步觀察:

首先是每個digit取得可以透過 %10得到的結果

然後在用/10 去shift到下一個digit

n = 234 => check n > 0 , n % 10 = 4, n /= 10 

n = 23 => check n > 0 , n % 10 = 3, n /= 10

n = 2 => check n > 0, n % 10 = 2, n /= 10

n = 0

### 初步設計:

given an integer n

step 0: let a integer sum = 0, a integer product = 1

step 1: if n <= 0 go to step 3

step 2:  sum += n%10, product*= n%10, n/=10, go to step1

step 3: return product - sum

## 遇到的困難

### 題目上理解的問題

因為英文不是筆者母語

所以在題意解讀上 容易被英文用詞解讀給搞模糊

### pseudo code撰寫

一開始不習慣把pseudo code寫下來

因此 不太容易把自己的code做解析

### golang table driven test不熟

對於table driven test還不太熟析

所以對於寫test還是耗費不少時間

## 我的github source code

```golang

package subtract_product_sum

func subtractProductAndSum(n int) int {

	sum := 0

	product := 1

	for n > 0 {

		digit := n % 10

		sum += digit

		product *= digit

		n /= 10

	}

	return product - sum

}

```

## 測資的撰寫

```golang

package subtract_product_sum

import "testing"

func Test_subtractProductAndSum(t *testing.T) {

	type args struct {

		n int

	}

	tests := []struct {

		name string

		args args

		want int

	}{

		{

			name: "Example1",

			args: args{

				n: 234,

			},

			want: 15,

		},

		{

			name: "Example2",

			args: args{

				n: 4421,

			},

			want: 21,

		},

	}

	for _, tt := range tests {

		t.Run(tt.name, func(t *testing.T) {

			if got := subtractProductAndSum(tt.args.n); got != tt.want {

				t.Errorf("subtractProductAndSum() = %v, want %v", got, tt.want)

			}

		})

	}

}

```

## my self record

[golang ironman 30 day 10th day](https://hackmd.io/E2GK2K9fRf2zi9gKsrOyaA?view)

## 參考文章

[golang test](https://ithelp.ithome.com.tw/articles/10204692)