day05 update

app/src/main/kotlin/day05/Day05.kt

@@ -33,32 +33,14 @@ class Day05 {
         return true
     }
 
-    fun fixOrder(rules: HashMap<Int, List<Int>>, update: List<Int>): List<Int> {
-        var modUpdate = update.toMutableList()
-        for (i in 0..<update.count()) {
-            val curPage = modUpdate[i]
-            val curRule = rules[curPage]
-            if (curRule == null) { continue }
-            for (pre in 0..<i) {
-                if (curRule.contains(modUpdate[pre])) {
-                    modUpdate[i] = modUpdate[pre]
-                    modUpdate[pre] = curPage
-                    break
-                }
-            }
-        }
-        // hate this but im lazy
-        if (!checkOrder(rules, modUpdate)) {
-            modUpdate = fixOrder(rules, modUpdate).toMutableList()
-        }
-        return modUpdate
-    }
-
     fun part2(input: String): Int {
         val (rules, updates) = parse(input)
         return updates.filter {update -> !checkOrder(rules, update) }
-            .map { update -> fixOrder(rules, update) }
-            .map { update -> update[update.count() / 2] }
+        .flatMap { update ->
+            update.filter { curPage ->
+                rules[curPage]?.filter { update.contains(it) }?.count() == update.count() / 2
+            }
+        }
         .sum()
     }
 }