Big update: Adding all advent of codes to same repo

AdventOfCode2020/day9/day9.java

@@ -0,0 +1,101 @@
+import java.util.Scanner;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.util.ArrayList;
+
+class day9 {
+
+    public static void main(String[] args) {
+        
+        File myFile = new File("input.txt");
+        try {
+            
+            Scanner in = new Scanner(myFile);
+            ArrayList<Long> nums = new ArrayList<>();
+            
+            while (in.hasNext()) {
+                nums.add(Long.parseLong(in.nextLine()));
+            }
+
+            //final int preamble = 25;
+            //int lower = 0;
+            
+            long target = 1309761972;
+
+            for (int i = 0; i < nums.size() - 1; i++) {
+
+                boolean over = false;
+                long sum = 0;
+
+
+                ArrayList<Long> currentSet = new ArrayList<>();
+
+                for (int j = i; j < nums.size() && over == false; j++) {
+
+                    sum += nums.get(j);
+                    currentSet.add(nums.get(j));
+
+                    if (sum == target) {
+
+                        long highest = 0;
+                        long lowest = Long.MAX_VALUE;
+
+                        for (int k = 0; k < currentSet.size(); k++) {
+                            long current = currentSet.get(k);
+                            if (current < lowest) lowest = current;
+                            if (current > highest) highest = current;
+                        }
+
+                        over = true;
+
+                        System.out.println("Lowest: " + lowest);
+                        System.out.println("highest: " + highest);
+
+                        System.out.println(highest + lowest);
+                        break;
+
+                    } else if (sum > target) {
+                        over = true;
+                    }
+
+                }
+
+            }
+
+            //Part 1, very inefficient code, had no time to do this one today
+            //Made easier using a stack and an array to which the combination of numbers in the stack would add up to
+            //Pop and remove from the stack and remove the last 25 items from array/list
+            //And that would be the most efficient with an efficiency of O(n^2)? instead of O(n^3) - I think, not sure
+            /*for (int currentNum = preamble; currentNum < nums.size(); currentNum++) {
+
+                boolean adds = false;
+
+                for (int i = currentNum - preamble; i < currentNum - 1; i++) {
+                    for (int j = i + 1; j < currentNum; j++) {
+
+                        System.out.printf("Adding %d and %d, Current Num: %d \n", nums.get(i), nums.get(j), nums.get(currentNum));
+
+                        if (nums.get(i) + nums.get(j) == nums.get(currentNum)) {
+                            adds = true;
+                        }
+
+                    }
+                }
+
+                System.out.println(adds);
+
+                if (!adds) {
+                    System.out.println(nums.get(currentNum));
+                    break;
+                }
+
+            }*/
+
+        } catch (FileNotFoundException e) {
+            e.printStackTrace();
+        }
+        
+    }
+    
+}