Day 17

2024/17/index2.ts

@@ -0,0 +1,42 @@
+const fs = require('fs');
+
+const input = fs.readFileSync(__dirname + '/input.txt', 'utf8');
+
+const lines = input.split("\n");
+
+let instructionsStr = lines[4].split(' ')[1];
+const instructions = instructionsStr.split(',').map((i: string) => parseInt(i));
+
+function run(a: bigint) {
+    return (((a & 7n) ^ 7n) ^ (a >> ((a & 7n) ^ 3n))) & 7n;
+}
+
+let regA = 0n;
+
+for (let i = instructions.length - 1; i >= 0; i--) {
+    for (let a = 0n; a < 8n; a++) {
+        const testA = (regA << 3n) + a;
+        const out = run(testA);
+        if (out === BigInt(instructions[i])) {
+            regA = testA;
+            break;
+        }
+    }
+}
+console.log(regA);
+
+/*
+b = a % 8;
+b = b ^ 3;
+c = a / (2 ** b)
+a = a / 4
+b = b ^ 4
+b = b ^ c
+
+x = (((a & 7) ^ 7) ^ (a / (2 ** ((a & 7) ^ 3)))) & 7
+*/
+
+/*
+a = a >> 3
+x = a & 7
+*/