Some cleanup, added a few comments all around

2020/Day 1/Solution.py

@@ -1,7 +1,14 @@
 target = 2020
-input_file = "/tmp/aocinput"
+input_file = "input.txt"
+
 
 def find_sum_of_two():
+    """
+    Find two numbers from a list that add to a target.
+    This is done by separating the numbers in a smaller than half and bigger than half of the target,
+    and trying to find a match that would complement the sum, rather than adding everything together.
+    :return: None
+    """
     large_n = []
     small_n = []
 
@@ -14,6 +21,7 @@ def find_sum_of_two():
             if number > target/2:
                 large_n.append(number)
             elif number == target/2:
+                # Used for "early" exit if we find twice the half
                 halftarget_count += 1
             else:
                 small_n.append(number)
@@ -24,6 +32,7 @@ def find_sum_of_two():
 
             line = file.readline()
 
+    # This was chosen in this order because of input I got : mainly large numbers
     for big_one in large_n:
         complement = target-big_one
         if complement in small_n:
@@ -32,7 +41,14 @@ def find_sum_of_two():
 
     print("No sum found that can reach {target}")
 
+
 def sum_search(target_sum, inputs):
+    """
+    Basically the same as above but for an arbitrary target and list of numbers.
+    :param target_sum: Sum that we are looking numbers to reach
+    :param inputs: List of numbers to search for a pair adding to target_sum
+    :return: The pair if found, False otherwise
+    """
     lower = []
     upper = []
 
@@ -42,6 +58,7 @@ def sum_search(target_sum, inputs):
         else:
             upper.append(num)
 
+    # As those list might be of a different repartition, search the smaller one while iterating on the larger one
     search_list = lower if len(lower) < len(upper) else upper
     iter_list = upper if len(lower) < len(upper) else lower
 
@@ -53,24 +70,29 @@ def sum_search(target_sum, inputs):
 
 
 def find_sum_of_three():
+    """
+    Find a triplet of number that reach a target when added together. This time, constructing a list by subtracting each
+    number to the target, and using this list to check if the we can find two other numbers that add up to it.
+    To put it another way, instead of searching for a,b and c in a+b+c = t, search for a,b in a+b = t-c for every c.
+    :return: None
+    """
     data = []
     subtracted_to_target = []
     with open(input_file) as file:
         line = file.readline()
         while line and line != "\n":
             data.append(int(line))
-            subtracted_to_target.append((target-data[-1],data[-1]))
+            subtracted_to_target.append((target-data[-1], data[-1]))
 
             line = file.readline()
 
+    # Honestly not sure if it helps
     data.sort()
 
     for sub_target in subtracted_to_target:
-        result = sum_search(sub_target[0],data)
+        result = sum_search(sub_target[0], data)
         if result:
             print(f"Sum found : {result[0]}+{result[1]}+{sub_target[1]} = {target}\nResult is {result[0]*result[1]*sub_target[1]}")
             return
 
     print("No sum found")
-
-