Add Python day 1, 2, and 3

main.py

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+import src.day_01.part_1
+import src.day_01.part_2
+import src.day_02.part_1
+import src.day_02.part_2
+import src.day_03.part_1
+import src.day_03.part_2

src/day_01/part_1.py

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+lines = [ line.strip().split("   ") for line in open('inputs/01.txt') ]
+
+left = [ int(line[0]) for line in lines ]
+right = [ int(line[1]) for line in lines ]
+
+left.sort()
+right.sort()
+
+s = 0
+
+for l, r in zip(left, right):
+    s += abs(l - r)
+
+print(f"Day 01 part 1: {s}")

src/day_01/part_2.py

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+lines = [ line.strip().split("   ") for line in open('inputs/01.txt') ]
+
+left = [ int(line[0]) for line in lines ]
+right = [ int(line[1]) for line in lines ]
+
+left.sort()
+right.sort()
+
+s = 0
+
+i, j = 0, 0
+
+while i < len(left) and j < len(right):
+    l, r = left[i], right[j]
+
+    if l < r:
+        i += 1
+    elif l > r:
+        j += 1
+    else:
+        j += 1
+        s += l
+
+print(f"Day 01 part 2: {s}")

src/day_02/part_1.py

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+import itertools
+
+lines = [ [ int(l) for l in line.strip().split(" ") ] for line in open('inputs/02.txt') ]
+
+s = 0
+
+for line in lines:
+    increasing, decreasing, max_diff = 0, 0, 0
+
+    for a, b in itertools.pairwise(line):
+        max_diff = max(max_diff, abs(a - b))
+
+        if a < b:
+            increasing += 1
+        elif a > b:
+            decreasing += 1
+    
+    single_direction = (increasing * decreasing == 0) and (increasing + decreasing == len(line) - 1)
+
+    if single_direction and max_diff <= 3:
+        s += 1
+
+print(f"Day 02 part 1: {s}")

src/day_02/part_2.py

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+import itertools
+
+def is_safe_line(line) -> bool:
+    increasing, decreasing, max_diff = 0, 0, 0
+
+    for a, b in itertools.pairwise(line):
+        max_diff = max(max_diff, abs(a - b))
+
+        if a < b:
+            increasing += 1
+        elif a > b:
+            decreasing += 1
+    
+    single_direction = (increasing * decreasing == 0) and (increasing + decreasing == len(line) - 1)
+
+    return single_direction and max_diff <= 3
+
+
+lines = [ [ int(l) for l in line.strip().split(" ") ] for line in open('inputs/02.txt') ]
+
+s = 0
+
+for line in lines:
+    if is_safe_line(line):
+        s += 1
+    else:
+        for i in range(len(line)):
+            if is_safe_line(line[:i] + line[i+1:]):
+                s += 1
+                break
+
+print(f"Day 02 part 2: {s}")

src/day_03/part_1.py

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+import re
+
+lines = "".join(line for line in open('inputs/03.txt'))
+total = 0
+
+for a, b in re.findall(r"mul\((\d{1,3}),(\d{1,3})\)", lines):
+    total += int(a) * int(b)
+
+print(f"Day 03 part 1: {total}")

src/day_03/part_2.py

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+import re
+
+def find_muls(text : str) -> int:
+    tot = 0
+    for a, b in re.findall(r"mul\((\d{1,3}),(\d{1,3})\)", text):
+        tot += int(a) * int(b)
+    return tot
+
+lines = "".join(line for line in open('inputs/03.txt'))
+total = 0
+
+if "don't()" in lines:
+    parts = lines.split("don't()")
+
+    # By default, first is valid
+    total += find_muls(parts[0])
+
+    for part in parts[1:]:
+        for valid_part in part.split("do()")[1:]:
+            total += find_muls(valid_part)
+else:
+    total = find_muls(lines)
+
+print(f"Day 03 part 2: {total}")