Completed Year 2022 Day 6 Part 1

2022/README.md

@@ -161,5 +161,19 @@ techniques should be used.
 
 ## Day 6
 
+- [The problem](https://adventofcode.com/2022/day/6)
+- [The solution](src/main/java/edu/unl/cse/bohn/year2022/Day6.java)
+
+### Part 1
+
+The subproblems are
+- Identify the first sequence of four unique characters in a string
+  - Assume there is such a sequence
+  - Determine when a sequence of four characters contain duplicates
+- Count the number of characters before the next character after that sequence
+  - *i.e.*, count the number of characters before that sequence plus the four characters in that sequence
+
+## Day 7
+
 (coming soon)
 

2022/src/main/java/edu/unl/cse/bohn/year2022/Day6.java

+package edu.unl.cse.bohn.year2022;
+
+import edu.unl.cse.bohn.Puzzle;
+
+import java.util.*;
+
+@SuppressWarnings("unused")
+public class Day6 extends Puzzle {
+    @SuppressWarnings({"SpellCheckingInspection", "CommentedOutCode"})
+    public Day6(boolean isProductionReady) {
+        super(isProductionReady);
+//        sampleData = "mjqjpqmgbljsphdztnvjfqwrcgsmlb";
+//        sampleData = "bvwbjplbgvbhsrlpgdmjqwftvncz";
+//        sampleData = "nppdvjthqldpwncqszvftbrmjlhg";
+//        sampleData = "nznrnfrfntjfmvfwmzdfjlvtqnbhcprsg";
+        sampleData = "zcfzfwzzqfrljwzlrfnpqdbhtmscgvjw";
+    }
+
+    @Override
+    public long computePart1(List<String> data) {
+        return getStartOfPacketIndex(data.get(0));
+    }
+
+    @Override
+    public long computePart2(List<String> data) {
+        return 0;
+    }
+
+    private long getStartOfPacketIndex(String dataStream) {
+        LinkedList<Character> markerCandidate = new LinkedList<>();
+        int nextIndex = 0;
+        int indexOfDuplicate = Integer.MIN_VALUE;
+        boolean foundMarker = false;
+        while (!foundMarker) {
+            char c = dataStream.charAt(nextIndex++);
+//            System.out.print(markerCandidate + " + " + c + " = ");
+            int indexOfPossibleDuplicate = markerCandidate.lastIndexOf(c);
+            indexOfDuplicate = Integer.max(indexOfDuplicate, indexOfPossibleDuplicate);
+            markerCandidate.add(c);
+            if (nextIndex > 4) {
+                markerCandidate.remove();
+                indexOfDuplicate--;
+                if (indexOfDuplicate < 0) {
+                    foundMarker = true;
+                }
+            }
+//            System.out.println(markerCandidate);
+        }
+        return nextIndex;
+    }
+}