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day13.js
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day13.js
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const fs = require('fs');
const input = fs.readFileSync('./example', 'utf-8');
const signalPairs = input.split('\n\n');
const signals = signalPairs.map(p => {
let signal = p.split('\n').map(s => JSON.parse(s));
return {
left: signal[0],
right: signal[1],
};
});
function compare(left, right) {
if (!Array.isArray(left) && !Array.isArray(right)) {
return Math.sign(right - left);
} else if (!Array.isArray(left) && Array.isArray(right)) {
return compare([left], right);
} else if (Array.isArray(left) && !Array.isArray(right)) {
return compare(left, [right]);
} else if (Array.isArray(left) && Array.isArray(right)) {
const min = Math.min(left.length, right.length);
for (let i = 0; i < min; i++) {
const c = compare(left[i], right[i]);
if (c !== 0) {
return c;
}
}
if (left.length == right.length) {
return 0;
} else if (left.length <= min) {
return 1;
} else {
return -1;
}
}
return -1;
}
let valid = [];
let index = 1;
for (let signal of signals) {
if (compare(signal.left, signal.right) === 1) {
valid.push(index);
}
index += 1;
}
console.log('Part 1:', valid.reduce((sum, i) => sum + i, 0));
let sortedSignals = [];
for (let signal of signals) {
sortedSignals.push({
isDivider: false,
signal: signal.left,
});
sortedSignals.push({
isDivider: false,
signal: signal.right,
});
}
sortedSignals.push({
isDivider: true,
signal: [[2]],
});
sortedSignals.push({
isDivider: true,
signal: [[6]],
})
sortedSignals.sort((a, b) => compare(a.signal, b.signal));
sortedSignals.reverse();
let i = 1;
let sum = 1;
for (let signal of sortedSignals) {
console.log(JSON.stringify(signal.signal));
if (signal.isDivider) {
sum *= i;
}
i += 1;
}
console.log('Part 2:', sum);