Day 24 Part 2 Attempt

2024/24/index2.ts

@@ -23,13 +23,36 @@ initStr.split("\n").forEach((s: string) => {
 });
 valMap = {...originalValMap};
 
-gatesStr.split("\n").forEach((s: string) => {
+const carries: Array<string> = [];
+const halfAdds: Array<string> = [];
+const badOuts: Array<string> = [];
+const badAnds: Array<string> = [];
+
+const gates: Array<[string, string, string, string]> = gatesStr.split("\n").map((s: string) => {
     const [inp, out] = s.split(' -> ');
     const [val1, op, val2] = inp.split(' ');
+    return [val1, op, val2, out];
+});
+gates.forEach(([val1, op, val2, out]) => {
     gateMap[out] = [val1, op, val2];
     if (out.startsWith('z')) {
         outputWires.push(out);
     }
+    if ((op === 'XOR' && !val1.startsWith('x') && !val1.startsWith('y')) || (op === 'XOR' && (val1 === 'x00' || val1 === 'y00'))) {
+        if (!out.startsWith('z')) {
+            badOuts.push(out);
+        }
+    } else if (out.startsWith('z')) {
+        badOuts.push(out);
+    }
+    if (op === 'AND') {
+        for (let [val1, op, val2] of gates) {
+            if (op !== 'OR' && (val1 === out || val2 === out)) {
+                badAnds.push(out);
+                break;
+            }
+        }
+    }
 });
 
 function getWireVal(wire: string, trace: Array<string> = []): number {
@@ -58,7 +81,6 @@ function getVal(wire1: string, op: string, wire2: string, trace: Array<string> =
 
 outputWires.sort().reverse();
 
-
 function calculate() {
     let outputStr = '';
     valMap = {...originalValMap};
@@ -68,56 +90,65 @@ function calculate() {
     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++;
+function getPermutations(arr: Array<string>): Array<Array<string>> {
+    if (arr.length === 1) {
+        return [arr];
     }
-    }
-    return mistakes;
+    return arr.flatMap((s, i) => {
+        return getPermutations([...arr.slice(0, i), ...arr.slice(i + 1)]).map((p) => [s, ...p]);
+    });
 }
 
-let fewestMistakes: number|null = null;
-let bestSwap: [string, string]|null = null;
-let swapResult: string|null = null;
-
-const wires = Object.keys(gateMap);
+function swap(wire1: string, wire2: string): void {
+    const wire1Gate = gateMap[wire1];
+    const wire2Gate = gateMap[wire2];
+    gateMap[wire1] = wire2Gate;
+    gateMap[wire2] = wire1Gate;
+}
 
 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;
+const zOutputsToSwap = badOuts.filter((o) => o[0] === 'z');
+const otherOutputsToSwap = badOuts.filter((o) => o[0] !== 'z');
 
-        let actual;
+for (let perm of getPermutations(zOutputsToSwap)) {
+    swap(perm[0], otherOutputsToSwap[0]);
+    swap(perm[1], otherOutputsToSwap[1]);
+    swap(perm[2], otherOutputsToSwap[2]);
+
+    for (let i = 0; i < gates.length - 1; i++) {
+        for (let j = i + 1; j < gates.length; j++) {
+            swap(gates[i][3], gates[j][3]);
             try {
-            actual = calculate();
+                const output = calculate();
+                if (output === expected) {
+                    const swaps = [...perm, ...otherOutputsToSwap, gates[i][3], gates[j][3]];
+                    swaps.sort();
+                    console.log(swaps);
+                    break;
+                }
             } catch (e) {
-            continue;
+                //
             } finally {
-            gateMap[wireA] = gateA;
-            gateMap[wireB] = gateB;
+                swap(gates[i][3], gates[j][3]);
+            }
+        }
     }
-        const mist = mistakes(actual, expected);
 
-        if (!fewestMistakes || fewestMistakes > mist) {
-            fewestMistakes = mist;
-            bestSwap = [wireA, wireB];
-            swapResult = actual;
-        }
-    }
+    swap(perm[0], otherOutputsToSwap[0]);
+    swap(perm[1], otherOutputsToSwap[1]);
+    swap(perm[2], otherOutputsToSwap[2]);
 }
 
-console.log(xStr);
-console.log(yStr);
-console.log(expected);
-console.log(calculate());
-console.log(fewestMistakes);
-console.log(bestSwap);
-console.log(swapResult);
+/*
+ * 1234
+ * 4123
+ * 3412
+ * 2341
+ * 4321
+ * 1432
+ * 2143
+ * 3214
+ * 1324
+ * 4132
+*/