Go 言語で「基礎プログラミング演習 I 〜100 本ノック初級編」を解いてみる-No.28「n の階乗」

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$ uname -moi
x86_64 unknown GNU/Linux

$ head -n 2 /etc/os-release
PRETTY_NAME="Debian GNU/Linux 10 (buster)"
NAME="Debian GNU/Linux"

$ go version | head -n 1
go version go1.16.3 linux/amd64

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# 【実行例、下線部は入力例】
$ ./knock28
input number: 10
factorial = 3628800

$ ./knock28
input number: -2
factorial = 1

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package main

import (
	"fmt"
)

func main() {
	var n int

	fmt.Printf("input number: ")
	fmt.Scan(&n)

	fmt.Printf("factorial = %v\n", factorial(n))
}

func factorial(n int) int {
	if n <= 0 {
		return 1
	} else {
		return n * factorial(n-1)
	}
}

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$ go run knock28.go
input number: 10
factorial = 3628800

$ go run knock28.go
input number: -2
factorial = 1

$ go run knock28.go
input number: 0
factorial = 1

$ go run knock28.go
input number: 1
factorial = 1

$ go run knock28.go
input number: 2
factorial = 2

$ go run knock28.go
input number: 3
factorial = 6