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133 lines
3.4 KiB
Zig

const std = @import("std");
const mem = std.mem;
const Symbol = enum(u2) {
M,
U,
I
};
pub fn main() !void {
// Prints to stderr (it's a shortcut based on `std.io.getStdErr()`)
std.debug.print("All your {s} are belong to us.\n", .{"codebase"});
// stdout is for the actual output of your application, for example if you
// are implementing gzip, then only the compressed bytes should be sent to
// stdout, not any debugging messages.
const stdout_file = std.io.getStdOut().writer();
var bw = std.io.bufferedWriter(stdout_file);
const stdout = bw.writer();
var list = std.ArrayList([]Symbol).init(std.heap.page_allocator);
defer list.deinit(); // try commenting this out and see if zig detects the memory leak!
var initial: [2]Symbol = .{Symbol.M, Symbol.I};
try list.append(&initial);
var count: u64 = 0;
while(list.items.len > count){
count = list.items.len;
for(list.items)|string|{
if(rule1Test(string)){ try list.append(rule1(string)); }
if(rule2Test(string)){ try list.append(rule2(string)); }
if(rule3Test(string)){ try list.append(rule3(string)); }
if(rule4Test(string)){ try list.append(rule4(string)); }
if(finish(string)){
break; //Finished!
}
}
}
try stdout.print("Run `zig build test` to run the tests.\n", .{});
try bw.flush(); // don't forget to flush!
}
pub fn rule1Test(input: []Symbol ) bool{
return (input[input.len] == Symbol.I);
}
pub fn rule1(input: []Symbol) []Symbol{
const lastEl:Symbol = input[input.len];
if(lastEl == Symbol.I){
return input ++ &Symbol.U;
}
}
pub fn rule2Test(input: []Symbol) bool {
return input[0] == Symbol.M;
}
pub fn rule2(input: []Symbol) []Symbol{
//M_ => M__
return input ++ input[1..];
}
pub fn rule3Test(input: []Symbol) bool {
for(input)|symbol, i|{
if(symbol == Symbol.I){
var streak = input[i..i+2];
if(mem.eql(u2, streak, [_]Symbol{Symbol.I ** 3}) ){
return true;
}
}
}
return false;
}
pub fn rule3(input: []Symbol) []Symbol{
// III => U
//var i:u64 = 0;
for(input)|symbol, i|{
if(symbol == Symbol.I){
var streak = input[i..i+2];
if(mem.eql(u2, streak, []Symbol{Symbol.I ** 3})){
return input[0..i] ++ Symbol.U ++ input[i+2..];
}
}
}
}
pub fn rule4Test(input: []Symbol) bool {
for(input)|symbol, i|{
if(symbol == Symbol.U){
var streak = input[i..i+2];
return (mem.eql(u2, streak, []Symbol{Symbol.U ** 3}));
}
}
return false;
}
pub fn rule4(input: []Symbol) []Symbol{
// UU => -
for(input)|symbol, i|{
if(symbol == Symbol.U){
var streak = input[i..i+2];
if(mem.eql(u2, streak, []Symbol{Symbol.U ** 3})){
return input[0..i] ++ input[i+1..];
}
}
}
}
pub fn finish(input: []Symbol) bool{
return mem.eql(u2, input, []Symbol{Symbol.M, Symbol.U});
}
test "simple test" {
var list = std.ArrayList(i32).init(std.testing.allocator);
defer list.deinit(); // try commenting this out and see if zig detects the memory leak!
try list.append(42);
try std.testing.expectEqual(@as(i32, 42), list.pop());
}