day 16 complete

.aocrunner.json

@@ -227,16 +227,16 @@
     },
     {
       "part1": {
-        "solved": false,
-        "result": null,
+        "solved": true,
+        "result": "852",
         "attempts": [],
-        "time": null
+        "time": 0.78
       },
       "part2": {
-        "solved": false,
-        "result": null,
+        "solved": true,
+        "result": "19348959966392",
         "attempts": [],
-        "time": null
+        "time": 0.62
       }
     },
     {

README.md

@@ -26,7 +26,7 @@
 [![Day](https://badgen.net/badge/13/%E2%98%85%E2%98%85/green)](src/day13)
 [![Day](https://badgen.net/badge/14/%E2%98%85%E2%98%85/green)](src/day14)
 [![Day](https://badgen.net/badge/15/%E2%98%85%E2%98%85/green)](src/day15)
-![Day](https://badgen.net/badge/16/%E2%98%86%E2%98%86/gray)
+[![Day](https://badgen.net/badge/16/%E2%98%85%E2%98%85/green)](src/day16)
 ![Day](https://badgen.net/badge/17/%E2%98%86%E2%98%86/gray)
 ![Day](https://badgen.net/badge/18/%E2%98%86%E2%98%86/gray)
 ![Day](https://badgen.net/badge/19/%E2%98%86%E2%98%86/gray)
@@ -167,16 +167,16 @@ Both parts: 6.279999999999999ms
 
 ```
 Day 15
-Time part 1: 8.12ms
-Time part 2: 769.36ms
-Both parts: 777.48ms
+Time part 1: 55.8ms
+Time part 2: 761.32ms
+Both parts: 817.12ms
 ```
 
 ```
 Day 16
-Time part 1: -
-Time part 2: -
-Both parts: -
+Time part 1: 0.78ms
+Time part 2: 0.62ms
+Both parts: 1.4ms
 ```
 
 ```
@@ -243,8 +243,8 @@ Both parts: -
 ```
 
 ```
-Total stars: 30/50
-Total time: 1861.9599999999996ms
+Total stars: 32/50
+Total time: 1902.9999999999998ms
 ```
 
 <!--/RESULTS-->

src/day16/index.js

@@ -11,75 +11,128 @@ function b2d(binaryString) {
   return parseInt(binaryString, 2)
 }
 
-const part1 = (rawInput) => {
-  const input = parseInput(rawInput)
-  let cursor = 0,
-    ans = 0
+function readPacket1(s) {
+  if (/^0+$/.test(s)) return [0, ""]
+  let cursor = 0
   function read(n) {
     cursor += n
-    return input.substr(cursor - n, n)
-  }
-  const stack = [{ count: 1 }]
-  while (stack.length) {
-    const thisLimit = stack[0]
-    if (thisLimit.count !== undefined) {
-      --thisLimit.count
-      if (thisLimit.count == 0) {
-        stack.shift()
-      }
-    }
-    if (thisLimit.cursor !== undefined) {
-      if (cursor >= thisLimit.cursor) {
-        stack.shift()
-      }
+    return s.substr(cursor - n, n)
   }
   const version = b2d(read(3))
   const typeId = b2d(read(3))
   if (typeId === 4) {
     // literal value
-      ans += version
     let acc = ""
     for (let more = 1; more; ) {
       more = +read(1)
       acc += read(4)
     }
+    return [version, s.substr(cursor)]
   } else {
     // operator type
     const lengthTypeId = +read(1)
     if (lengthTypeId == 0) {
       const subpacketLength = b2d(read(15))
-        ans += version
-        stack.unshift({ cursor: cursor + subpacketLength })
+      let nextV, nextS = read(subpacketLength)
+      let versionSum = version
+      while (nextS.length > 0) {
+        [nextV, nextS] = readPacket1(nextS)
+        versionSum += nextV
+      }
+      return [versionSum, s.substr(cursor)]
     } else {
       const subpacketCount = b2d(read(11))
-        ans += version
-        stack.unshift({ count: subpacketCount })
+      let nextV, nextS = s.substr(cursor)
+      let versionSum = version
+      for (let i = 0; i < subpacketCount; i++) {
+        [nextV, nextS] = readPacket1(nextS)
+        versionSum += nextV
+      }
+      return [versionSum, nextS]
     }
   }
+}
+
+const part1 = (rawInput) => {
+  const input = parseInput(rawInput)
+  return readPacket1(input)[0]
+}
+
+const operators = [
+  (...args) => args.reduce((a,c) => a+c, 0), // sum,
+  (...args) => args.reduce((a,c) => a*c, 1), // product
+  Math.min, // minimum,
+  Math.max, // maximum,
+  null, // omitted
+  (a,b) => a > b ? 1 : 0, // greater than
+  (a,b) => a < b ? 1 : 0, // less than
+  (a,b) => a == b ? 1 : 0, // equals
+]
+
+function readPacket2(s) {
+  if (/^0+$/.test(s)) return [undefined, ""]
+  let cursor = 0
+  function read(n) {
+    cursor += n
+    return s.substr(cursor - n, n)
+  }
+  read(3) // version, read and discard
+  const typeId = b2d(read(3))
+  if (typeId === 4) {
+    // literal value
+    let acc = ""
+    for (let more = 1; more; ) {
+      more = +read(1)
+      acc += read(4)
+    }
+    return [parseInt(acc, 2), s.substr(cursor)]
+  } else {
+    // operator type
+    const lengthTypeId = +read(1)
+    if (lengthTypeId == 0) {
+      const subpacketLength = b2d(read(15))
+      const values = []
+      let nextValue, nextS = read(subpacketLength)
+      while (nextS.length > 0) {
+        [nextValue, nextS] = readPacket2(nextS)
+        values.push(nextValue)
+      }
+      return [operators[typeId](...values), s.substr(cursor)]
+    } else {
+      const subpacketCount = b2d(read(11))
+      const values = []
+      let nextValue, nextS = s.substr(cursor)
+      for (let i = 0; i < subpacketCount; i++) {
+        [nextValue, nextS] = readPacket2(nextS)
+        values.push(nextValue)
+      }
+      return [operators[typeId](...values), nextS]
+    }
   }
-  return ans
 }
 
 const part2 = (rawInput) => {
   const input = parseInput(rawInput)
-
-  return
+  return readPacket2(input)[0]
 }
 
 run({
   part1: {
     tests: [
       { input: `D2FE28`, expected: 6 },
-      // { input: `8A004A801A8002F478`, expected: 16 },
-      // { input: `620080001611562C8802118E34`, expected: 12 },
-      // { input: `C0015000016115A2E0802F182340`, expected: 23 },
-      // { input: `A0016C880162017C3686B18A3D4780`, expected: 31 },
+      { input: `8A004A801A8002F478`, expected: 16 },
+      { input: `620080001611562C8802118E34`, expected: 12 },
+      { input: `C0015000016115A2E0802F182340`, expected: 23 },
+      { input: `A0016C880162017C3686B18A3D4780`, expected: 31 },
     ],
     solution: part1,
   },
   part2: {
     tests: [
-      // { input: ``, expected: "" },
+      { input: `C200B40A82`, expected: 3 },
+      { input: `04005AC33890`, expected: 54 },
+      { input: `880086C3E88112`, expected: 7 },
+      { input: `CE00C43D881120`, expected: 9 },
     ],
     solution: part2,
   },