2024/22 off by one

Author: encse

2024/Day22/Solution.cs

@@ -8,7 +8,7 @@ namespace AdventOfCode.Y2024.Day22;
 class Solution : Solver {
 
     public object PartOne(string input) {
-       return GetNums(input).Select(x => (long)SecretNumbers(x).Last()).Sum();
+        return GetNums(input).Select(x => (long)SecretNumbers(x).Last()).Sum();
     }
 
     public object PartTwo(string input) {
@@ -17,7 +17,7 @@ public object PartTwo(string input) {
         var buyingOptions = new Dictionary<string, int>();
         foreach (var num in GetNums(input)) {
             var optionsBySeller = BuyingOptions(num);
-            foreach(var seq in optionsBySeller.Keys){
+            foreach (var seq in optionsBySeller.Keys) {
                 buyingOptions[seq] = buyingOptions.GetValueOrDefault(seq) + optionsBySeller[seq];
             }
         }
@@ -32,24 +32,24 @@ Dictionary<string, int> BuyingOptions(int seed) {
         // a sliding window of 5 elements over the sold bananas defines the sequence the monkey 
         // will recognize. add the first occurrence of each sequence to the buyOptions dictionary 
         // with the corresponding banana count
-        for (var i = 5;i < bananasSold.Length; i++) {
-            var slice = bananasSold[(i-5) .. i];
-            var seq = string.Join(",", Diff(slice)); 
+        for (var i = 0; i <= bananasSold.Length - 5; i++) {
+            var slice = bananasSold[i..(i + 5)];
+            var seq = string.Join(",", Diff(slice));
             if (!buyOptions.ContainsKey(seq)) {
                 buyOptions[seq] = slice.Last();
             }
         }
         return buyOptions;
     }
-    int[] Bananas(int seed)  => SecretNumbers(seed).Select(n => n % 10).ToArray();
+    int[] Bananas(int seed) => SecretNumbers(seed).Select(n => n % 10).ToArray();
 
     int[] Diff(IEnumerable<int> x) => x.Zip(x.Skip(1)).Select(p => p.Second - p.First).ToArray();
 
     IEnumerable<int> SecretNumbers(int seed) {
         var mixAndPrune = (int a, long b) => (int)((a ^ b) % 16777216);
-        
+
         yield return seed;
-        for(var i = 0;i< 2000;i++) {
+        for (var i = 0; i < 2000; i++) {
             seed = mixAndPrune(seed, seed * 64L);
             seed = mixAndPrune(seed, seed / 32L);
             seed = mixAndPrune(seed, seed * 2048L);