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mod tensor;
use std::io::{BufRead};
pub type Matrix<T> = tensor::Tensor<T, 2>;
pub type Index = tensor::Index<2>;
pub fn main() {
let stdin = std::io::stdin();
let handle = stdin.lock();
let mut energy: Matrix<usize> = {
let mut tmp: Vec<usize> = Vec::new();
let mut m: usize = 0;
for l in handle.lines() {
let line = l.unwrap();
tmp.extend(line.chars().map(|c| c.to_digit(10).unwrap() as usize));
m += 1;
}
let n = tmp.len()/m;
Matrix::new_from([m, n], tmp)
};
let m = energy.shape()[0];
let n = energy.shape()[1];
let mut can_flash: Matrix<bool> = Matrix::new(energy.shape().clone(), true);
let mut to_increase: Vec<Index> = Vec::new();
for s in 0.. {
can_flash.fill(true);
to_increase.clear();
for i in 0..m {
for j in 0..n {
to_increase.push([i, j]);
}
}
while let Some(idx) = to_increase.pop() {
if can_flash[idx] {
energy[idx] += 1;
if energy[idx] > 9 {
let neighbors: [Index; 8] = [[idx[0] , idx[1].wrapping_sub(1)], [idx[0] , idx[1]+1],
[idx[0].wrapping_sub(1) , idx[1] ], [idx[0]+1, idx[1] ],
[idx[0].wrapping_sub(1) , idx[1].wrapping_sub(1)], [idx[0]+1, idx[1]+1],
[idx[0].wrapping_sub(1) , idx[1]+1 ], [idx[0]+1, idx[1].wrapping_sub(1)] ];
energy[idx] = 0;
can_flash[idx] = false;
for neighbor in (& neighbors).into_iter().filter(|neighbor| energy.in_bounds(neighbor)) {
to_increase.push(*neighbor);
}
}
}
}
let e = energy[[0,0]];
if energy.data().into_iter().all(|& x| x == e) {
println!("Synchronized after step {} (so answer is step {})", s, s+1);
break;
}
}
}
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