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use std::ops::Add;
fn cycles(op: &str) -> usize {
match op {
"noop" => 1,
"addx" => 2,
unk => panic!("unknown op {}", unk)
}
}
fn op_and_args(instruction: &str) -> (&str, Option<i32>) {
let mut toks = instruction.split_whitespace();
let op = toks.next().expect("expected an operator!");
let arg = match op {
"noop" => None,
"addx" => {
let arg1: i32 = toks.next().expect("expected one arg for addx").parse().expect("arg for addx must be i32");
Some(arg1)
},
unk => panic!("unknown op {}", unk)
};
(op,arg)
}
fn apply(op: &str, arg: Option<i32>, x: i32) -> i32 {
match op {
"noop" => x,
"addx" => x + arg.expect("addx had no argument!"),
unk => panic!("unknown op {}", unk)
}
}
pub fn run(input: String) {
let mut lines = input.lines().into_iter();
// our (single) register
let mut x = 1;
let mut tick = 1;
let first_instruction: &str = lines.next().expect("expected a first instruction!");
let (mut op, mut arg) = op_and_args(first_instruction);
let mut circ = cycles(op);
//let mut sss = 0;
let mut screen = "".to_owned();
loop {
// Start of cycle, Load next instruction
if circ == 0 {
if let Some(next_inst) = lines.next() {
(op, arg)= op_and_args(next_inst);
circ = cycles(op);
} else {
break;
}
}
// Time passes....
circ -= 1;
// Pt1, signal strength
// if (tick + 20) % 40 == 0 {
// let ss = tick*x;
// //println!("tick {} x {} ss {}", tick, x, ss);
// sss += ss;
// }
// Pt2, Draw pixels! note crt_col is one less(!) than tick
let crt_col = (tick-1) % 40;
//println!("tick {} x {} crt_col {}", tick, x, crt_col);
screen = screen.add(if crt_col >= (x-1) && crt_col <= (x+1) {
"#"
} else {
"."
});
if crt_col == 39 {
screen = screen.add("\n");
}
// End of cycle, apply instruction
if circ == 0 {
x = apply(op, arg, x);
}
// increase cycle counter
tick += 1;
}
//println!("Day 10: {}",sss);
println!("Day 10:");
print!("{}", screen);
}
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