day23 part 2

Author: chinesedfan

README.md

@@ -220,7 +220,7 @@ Different scripts for day 25,
 | 20  |   S/H    | picture matching/pattern search |
 | 21  |   M/S    | analyze insets                  |
 | 22  |   S/S    | cards array iteration           |
-| 23  |   S/-    | array iteration                 |
+| 23  |   S/S    | array iteration                 |
 | 24  |   S/S    | hex flip/life game simulation   |
 | 25  |   S/-    | number iteration                |
 

lib/2020/day23.js

@@ -1,4 +1,4 @@
-const MAX = 9
+let MAX = 9
 
 module.exports = function(part, data) {
     const numbers = data.split('').map(x => +x)
@@ -18,13 +18,32 @@ module.exports = function(part, data) {
         }
 
         result = []
-        let n = 8
+        let n = MAX - 1
         while (n--) {
             cur = cur.next
             result.push(cur.v)
         }
         result = result.join('')
     } else {
+        const nmax = 1000000
+        let prev = nodes[numbers[MAX - 1]]
+        for (let i = MAX + 1; i <= nmax; i++) {
+            prev.next = nodes[i] = { v: i }
+            prev = prev.next
+        }
+        nodes[nmax].next = nodes[numbers[0]]
+        MAX = nmax
+
+        let moves = 10000000
+        while (moves--) {
+            if (!(moves % 10000)) console.log(moves)
+
+            update(cur, nodes)
+            cur = cur.next
+        }
+
+        result = nodes[1].next.v * nodes[1].next.next.v
+        console.log(nodes[1].next.v, nodes[1].next.next.v)
     }
     console.log(result)
 }