diff --git a/aoc2020/lib/aoc2020.dart b/aoc2020/lib/aoc2020.dart
index 42e34f1..0fd3d53 100644
--- a/aoc2020/lib/aoc2020.dart
+++ b/aoc2020/lib/aoc2020.dart
@@ -7,6 +7,7 @@ import 'package:aoc2020/aoc20201206.dart';
 import 'package:aoc2020/aoc20201207.dart';
 import 'package:aoc2020/aoc20201208.dart';
 import 'package:aoc2020/aoc20201209.dart';
+import 'package:aoc2020/aoc20201210.dart';
 import 'package:aoc2020/aocbase.dart';
 import 'dart:mirrors';
 
@@ -26,6 +27,7 @@ class aoc2020 {
     AOC20201207(),
     AOC20201208(),
     AOC20201209(),
+    AOC20201210(),
   ];
 
   static void list() async {
diff --git a/aoc2020/lib/aoc20201210.dart b/aoc2020/lib/aoc20201210.dart
index 54b532c..8ccec1b 100644
--- a/aoc2020/lib/aoc20201210.dart
+++ b/aoc2020/lib/aoc20201210.dart
@@ -1,16 +1,68 @@
+import 'dart:math';
 import 'package:aoc2020/aocbase.dart';
 import 'package:aoc2020/model/readdata.dart';
 
 class AOC20201210 extends AOCBase {
+  var mylist = <num>[];
+  var dest = <num>[];
+
+  void init(bool test) async {
+    mylist = await ReadData.readFile<num>(classString, test: test);
+    mylist.sort();
+    mylist.insert(0, 0);
+    mylist.add(mylist.last + 3);
+    dest = [];
+    for (var index = 1; index < mylist.length; index++) {
+      dest.add(mylist[index] - mylist[index - 1]);
+    }
+  }
+
   @override
   Future<void> a({bool test}) async {
-    var filename = (test ?? false) ? classStringTest : classString;
-    var mylist = await ReadData.readFileString(filename);
+    await init(test);
+
+    var hist = <num, num>{};
+    for (var num in dest) {
+      hist[num] = hist[num] == null ? 1 : hist[num] + 1;
+    }
+    // print(hist);
+    answerA = hist[1] * hist[3];
   }
 
   @override
   Future<void> b({bool test}) async {
-    var filename = (test ?? false) ? classStringTest : classString;
-    var mylist = await ReadData.readFileString(filename);
+    var groups = <int, int>{};
+
+    await init(test);
+
+    // Count groups
+    var groupStart = false;
+    var groupCount = 0;
+    for (var index = 0; index < dest.length; index++) {
+      if (!groupStart && dest[index] == 1) {
+        groupStart = true;
+        groupCount = 0;
+      }
+      if (groupStart) {
+        if (dest[index] != 1) {
+          groupStart = false;
+          groups[groupCount] = groups[groupCount] == null ? 1 : groups[groupCount] + 1;
+        } else {
+          groupCount++;
+        }
+      }
+    }
+    var multiplier = <num>[1, 2, 4];
+    for (var index = 3; index < 30; index++) {
+      multiplier.add(multiplier[index-1] + multiplier[index-2] + multiplier[index-3]);
+    }
+    // print(groups);
+    answerB = 1;
+    for (var group in groups.keys) {
+      if (group > 1) {
+        // print('for group $group ${multiplier[group]} ^ ${groups[group]}');
+        answerB = answerB * pow(multiplier[group-1], groups[group]);
+      }
+    }
   }
 }
diff --git a/aoc2020/lib/data/aoc20201210.data b/aoc2020/lib/data/aoc20201210.data
new file mode 100644
index 0000000..ec74d95
--- /dev/null
+++ b/aoc2020/lib/data/aoc20201210.data
@@ -0,0 +1,99 @@
+18
+47
+144
+147
+124
+45
+81
+56
+16
+59
+97
+83
+75
+150
+33
+165
+30
+159
+84
+141
+104
+25
+164
+90
+92
+88
+2
+8
+51
+24
+153
+63
+27
+123
+127
+58
+108
+52
+38
+15
+149
+66
+72
+21
+46
+89
+135
+55
+34
+37
+78
+65
+134
+148
+76
+138
+103
+162
+114
+109
+42
+77
+102
+163
+7
+105
+69
+39
+91
+111
+131
+130
+6
+137
+96
+82
+64
+3
+95
+136
+85
+9
+116
+17
+99
+12
+117
+62
+50
+110
+26
+115
+71
+57
+156
+120
+98
+1
+70
diff --git a/aoc2020/lib/data/aoc20201210test.data b/aoc2020/lib/data/aoc20201210test.data
new file mode 100644
index 0000000..e6376dc
--- /dev/null
+++ b/aoc2020/lib/data/aoc20201210test.data
@@ -0,0 +1,31 @@
+28
+33
+18
+42
+31
+14
+46
+20
+48
+47
+24
+23
+49
+45
+19
+38
+39
+11
+1
+32
+25
+35
+8
+17
+7
+9
+4
+2
+34
+10
+3