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/*
中國古代數學家張丘建在他的《算經》
提出了一個著名的「百錢買百雞問題」，
雞翁一，值錢五，雞母一，值錢三，雞雛三，值錢一，
百錢買百雞，問翁、母、雛各幾何？
x = 翁
y = 母
z = 雛
5x+3y+z/3 =100(百錢)
x+y+z = 100(百雞)
0 <= x <= 100/5 ==> range = 20
0 <= y <= 100/3 ==> range = 33
0 <= z <= 100 ==> range = 100
*/
module main
fn main() {
mut x := 0
mut y := 0
mut z := 0
mut sum := 0
println("百錢買百雞問題")
for x = 0; x <= 20; x++ {
for y = 0; y <= 33; y++ {
for z = 0; z <= 100; z++ {
sum = 5 * x + 3 * y + z / 3
if sum == 100 && z % 3 == 0 && x + y + z == 100 {
println('翁:$x 母:$y 雛:$z')
}
}
}
}
}

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/*
================================================================
calculate pi with n digits
================================================================
*/
module main
const (
scale = 10000
arr_int = 20000
)
fn pi_digits(digits int) {
mut tm := 0
mut carry := 0
mut arr := [arr_int].repeat(arr_int + 1)
for i := digits; i > 0; i -= 4 {
mut sum := 0
for j := i; j > 0; j-- {
sum = sum * j + scale * arr[j]
arr[j] = sum % (j * 2 - 1)
sum /= j * 2 - 1
}
tm = carry + sum / scale
print('${tm:04d}')
carry = sum % scale
}
}
fn main() {
pi_digits(20000)
}

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module main
import os
struct Pagenode {
text string
mut:
choices &Choices
}
// /////////////////////////////////////////////////////////////////
struct Choices {
cmd string
description string
mut:
next_node &Pagenode
next_choice &Choices
}
fn new_page(text string) &Pagenode {
page := &Pagenode{text, 0}
return page
}
fn (mut node Pagenode) add_choice(cmd, description string, next_node &Pagenode) {
choice := &Choices{cmd, description, next_node, 0}
if node.choices == 0 {
node.choices = choice
} else {
mut current_choice := node.choices
for current_choice.next_choice != 0 {
current_choice = current_choice.next_choice
}
current_choice.next_choice = choice
}
}
fn (node Pagenode) render() {
println(node.text)
mut current_choice := node.choices
for current_choice != 0 {
println(current_choice.cmd + ' : ' + current_choice.description)
current_choice = current_choice.next_choice
}
}
fn (node Pagenode) execute_cmd(cmd string) &Pagenode {
mut current_choice := node.choices
for current_choice != 0 {
if current_choice.cmd.to_lower() == cmd.to_lower() {
return current_choice.next_node
}
current_choice = current_choice.next_choice
}
println('選個我看的懂的啦！')
return 0
}
fn (node Pagenode) play() {
node.render()
mut cmd := ''
if node.choices != 0 {
for cmd.len < 1 {
cmd = os.get_line().trim_space()
}
node.execute_cmd(cmd).play()
}
}
fn main() {
println('小白的冒險')
println('This is a nonesence damn story!!')
mut star := new_page('
嗯…一張開眼，你發現你在一個小小小的房間裏，昏暗的燈光下你看到有3個門…
驚不驚喜！！！
要不要開開看？
PS：不開就等著餓死吧！')
mut dark_room := new_page('伸手不見5指的房間')
mut dark_room_lit := new_page('有點小小亮光的房間')
grue := new_page('就是一個房間')
trap := new_page('哈一個該的陷阱！你死了。')
treasure := new_page('出○')
star.add_choice('N', '北門', dark_room)
star.add_choice('S', '南門', dark_room)
star.add_choice('E', '東門', trap)
dark_room.add_choice('S', '退回南門', grue)
dark_room.add_choice('O', '點亮臘燭！', dark_room_lit)
dark_room_lit.add_choice('N', '走北門', treasure)
dark_room_lit.add_choice('S', '走南門', star)
star.play()
println('結束了？？？')
}

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module main
fn main() {
mut prime_num := []int{}
mut nums := [2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25]
println(nums)
for nums.len > 1 {
prime_num << nums[0]
nums = nums.filter(it % nums[0] != 0)
}
prime_num << nums[0]
println(prime_num)
}

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