golang notes (6)---PAT (Basic Level) 1002-寫出這個數

using golang's math/big library, otherwise, one can use string to represent the input integer n(n <= 10^100).

package main

import (
	"fmt"
	"math/big"
)

func digits(n *big.Int) []int64 {
	d := make([]int64, 0)
	zero := big.NewInt(0)
	ten := big.NewInt(10)
	mod := big.NewInt(0)
	for n.Cmp(zero) > 0 {
		n, mod = n.DivMod(n, ten, mod)
		d = append(d, mod.Int64())
	}

	return d
}

func main() {
	var n big.Int
	_, err := fmt.Scanf("%v", &n)
	if err != nil {
		fmt.Println(err)
	}

	var d []int64 = digits(&n)
	//fmt.Println(d)
	sum := big.NewInt(0)
	for i := 0; i < len(d); i++ {
		sum = sum.Add(sum, big.NewInt(d[i]))
	}

	d = digits(sum)
	en2ch := map[int64]string{0:"ling", 1:"yi", 2:"er", 3:"san", 4:"si", 5:"wu", 6:"liu", 7:"qi", 8:"ba", 9:"jiu"}
	for i := len(d)-1; i >= 0; i-- {
		if i < len(d)-1 {
			fmt.Print(" ")
		}
		fmt.Print(en2ch[d[i]])
	}
	fmt.Print("\n")
}