Day 24 Part 1

2024/22/index.ts

@@ -0,0 +1,59 @@
+const fs = require('fs');
+
+const input = fs.readFileSync(__dirname + '/input.txt', 'utf8');
+
+function createSecret(secret: bigint) {
+    secret = ((secret << 6n) ^ secret) % 16777216n;
+    secret = ((secret >> 5n) ^ secret) % 16777216n;
+    return ((secret << 11n) ^ secret) % 16777216n;
+}
+
+
+let sum = 0n;
+
+const changeMap: { [key: string]: Array<number> } = {};
+
+input.split("\n").forEach((s: string, index: number) => {
+    let seed = BigInt(parseInt(s));
+    let seedStr = ''+seed;
+    const changes = [];
+    for (let i = 0; i < 2000; i++) {
+        const newSeed = createSecret(seed);
+        const newSeedStr = ''+newSeed;
+        const lastDig = parseInt(newSeedStr[newSeedStr.length - 1]);
+        const diff = lastDig - parseInt(seedStr[seedStr.length - 1]);
+        changes.push(diff);
+        if (i > 3) {
+            changes.shift();
+            const key = changes.join(',');
+            if (!changeMap[key]) {
+                changeMap[key] = [];
+            }
+            if (!changeMap[key][index]) {
+                changeMap[key][index] = lastDig;
+            }
+        }
+        seed = newSeed;
+        seedStr = newSeedStr;
+    }
+    sum += seed;
+});
+
+let highest: null|number = null;
+let highestSeq: null|string = null;
+
+for (let seq in changeMap) {
+    const prices = changeMap[seq];
+    let priceSum = 0;
+    prices.forEach((p) => {
+        if (p) {
+            priceSum += p;
+        }
+    });
+    if (!highest || priceSum > highest) {
+        highest = priceSum;
+        highestSeq = seq;
+    }
+}
+
+console.log(sum, highest, highestSeq);

2024/23/index.ts

@@ -0,0 +1,30 @@
+const fs = require('fs');
+
+const input = fs.readFileSync(__dirname + '/input.txt', 'utf8');
+
+const connections: { [key: string]: Array<string> }= {};
+
+input.split("\n").forEach((conn: string) => {
+    const [c1, c2] = conn.split('-');
+    connections[c1] = [c2, ...(connections[c1] || [])]
+    connections[c2] = [c1, ...(connections[c2] || [])]
+});
+
+const tCs = new Set;
+
+for (let key in connections) {
+    const conns = connections[key];
+    if (key.startsWith('t')) {
+        conns.forEach((c2) => {
+            connections[c2].forEach((c3) => {
+                if (connections[c3].includes(key)) {
+                    const arr = [key, c2, c3];
+                    arr.sort();
+                    tCs.add(arr.join(','));
+                }
+            })
+        })
+    }
+}
+
+console.log(tCs, tCs.size);

2024/24/index.ts

@@ -0,0 +1,54 @@
+const fs = require('fs');
+
+const input = fs.readFileSync(__dirname + '/input.txt', 'utf8');
+
+const [initStr, gatesStr] = input.split("\n\n");
+
+const valMap: { [key: string]: number }= {};
+const gateMap: { [key: string]: [string, string, string] } = {};
+
+const outputWires: Array<string> = [];
+
+initStr.split("\n").forEach((s: string) => {
+    const [wire, val] = s.split(': ');
+    valMap[wire] = parseInt(val, 2);
+});
+
+gatesStr.split("\n").forEach((s: string) => {
+    const [inp, out] = s.split(' -> ');
+    const [val1, op, val2] = inp.split(' ');
+    gateMap[out] = [val1, op, val2];
+    if (out.startsWith('z')) {
+        outputWires.push(out);
+    }
+});
+
+function getWireVal(wire: string): number {
+    if (Object.hasOwn(valMap, wire)) {
+        return valMap[wire];
+    }
+    const val = getVal(...gateMap[wire])
+    valMap[wire] = val;
+    return val;
+}
+
+function getVal(wire1: string, op: string, wire2: string): number {
+    const val1 = getWireVal(wire1);
+    const val2 = getWireVal(wire2);
+
+    return {
+        AND: () => val1 & val2,
+        OR: () => val1 | val2,
+        XOR: () => val1 ^ val2,
+    }[op]!();
+}
+
+outputWires.sort().reverse();
+
+let outputStr = '';
+
+outputWires.forEach((wire) => {
+    outputStr += getWireVal(wire);
+});
+
+console.log(outputStr, parseInt(outputStr, 2));

2024/24/index2.ts

@@ -0,0 +1,123 @@
+const fs = require('fs');
+
+const input = fs.readFileSync(__dirname + '/input.txt', 'utf8');
+
+const [initStr, gatesStr] = input.split("\n\n");
+
+const originalValMap: { [key: string]: number }= {};
+let valMap: { [key: string]: number } = {};
+const gateMap: { [key: string]: [string, string, string] } = {};
+
+let xStr = '';
+let yStr = '';
+const outputWires: Array<string> = [];
+
+initStr.split("\n").forEach((s: string) => {
+    const [wire, val] = s.split(': ');
+    originalValMap[wire] = parseInt(val, 2);
+    if (wire.startsWith('x')) {
+        xStr += val;
+    } else {
+        yStr += val;
+    }
+});
+valMap = {...originalValMap};
+
+gatesStr.split("\n").forEach((s: string) => {
+    const [inp, out] = s.split(' -> ');
+    const [val1, op, val2] = inp.split(' ');
+    gateMap[out] = [val1, op, val2];
+    if (out.startsWith('z')) {
+        outputWires.push(out);
+    }
+});
+
+function getWireVal(wire: string, trace: Array<string> = []): number {
+    if (Object.hasOwn(valMap, wire)) {
+        return valMap[wire];
+    }
+    const [wire1, op, wire2] = gateMap[wire];
+    if (trace.includes(wire1) || trace.includes(wire2)) {
+        throw Error('Cycle');
+    }
+    const val = getVal(wire1, op, wire2, [...trace, wire1, wire2]);
+    valMap[wire] = val;
+    return val;
+}
+
+function getVal(wire1: string, op: string, wire2: string, trace: Array<string> = []): number {
+    const val1 = getWireVal(wire1, trace);
+    const val2 = getWireVal(wire2, trace);
+
+    return {
+        AND: () => val1 & val2,
+        OR: () => val1 | val2,
+        XOR: () => val1 ^ val2,
+    }[op]!();
+}
+
+outputWires.sort().reverse();
+
+
+function calculate() {
+    let outputStr = '';
+    valMap = {...originalValMap};
+    outputWires.forEach((wire) => {
+        outputStr += getWireVal(wire);
+    });
+    return outputStr;
+}
+
+function mistakes(act: string, exp: string): number {
+    let mistakes = 0;
+    for (let i = 0; i < act.length; i++) {
+        if (act[i] !== exp[i]) {
+            mistakes++;
+        }
+    }
+    return mistakes;
+}
+
+let fewestMistakes: number|null = null;
+let bestSwap: [string, string]|null = null;
+let swapResult: string|null = null;
+
+const wires = Object.keys(gateMap);
+
+const expected = (parseInt(xStr, 2) + parseInt(yStr, 2)).toString(2);
+
+for (let i = 0; i < wires.length; i++) {
+    for (let j = i + 1; j < wires.length; j++) {
+        const wireA = wires[i];
+        const wireB = wires[j];
+        const gateA = gateMap[wireA];
+        const gateB = gateMap[wireB];
+        gateMap[wireA] = gateB;
+        gateMap[wireB] = gateA;
+
+        let actual;
+        try {
+            actual = calculate();
+        } catch (e) {
+            continue;
+        } finally {
+            gateMap[wireA] = gateA;
+            gateMap[wireB] = gateB;
+        }
+        const mist = mistakes(actual, expected);
+
+        if (!fewestMistakes || fewestMistakes > mist) {
+            fewestMistakes = mist;
+            bestSwap = [wireA, wireB];
+            swapResult = actual;
+        }
+    }
+}
+
+console.log(xStr);
+console.log(yStr);
+console.log(expected);
+console.log(calculate());
+console.log(fewestMistakes);
+console.log(bestSwap);
+console.log(swapResult);