Add day 4, 5, and 6

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

day05/day05.py

@@ -0,0 +1,97 @@
+#!/usr/bin/env python3
+from collections import defaultdict
+import dataclasses
+import sys
+from typing import DefaultDict, Generator, Sequence, Tuple
+import re
+from itertools import repeat
+import pprint
+
+
+SEG_PAT = re.compile(r"(?P<x1>[\d]+),(?P<y1>[\d]+) -> (?P<x2>[\d]+),(?P<y2>[\d]+)")
+
+
+@dataclasses.dataclass
+class Seg:
+    x1: int
+    y1: int
+    x2: int
+    y2: int
+
+    @staticmethod
+    def from_str(s: str) -> "Seg":
+        match = SEG_PAT.match(s)
+        assert match
+        return Seg(
+            int(match["x1"]), int(match["y1"]), int(match["x2"]), int(match["y2"])
+        )
+
+    def points(self, diag: bool) -> Generator[Tuple[int, int], None, None]:
+        if self.x1 == self.x2:
+            # We're going up and down
+            if self.y1 > self.y2:
+                lo = self.y2
+                hi = self.y1
+            else:
+                lo = self.y1
+                hi = self.y2
+            yield from zip(repeat(self.x1), range(lo, hi + 1))
+        elif self.y1 == self.y2:
+            # We're going side to side
+            if self.x1 > self.x2:
+                lo = self.x2
+                hi = self.x1
+            else:
+                lo = self.x1
+                hi = self.x2
+            yield from zip(range(lo, hi + 1), repeat(self.y1))
+        elif diag:
+            # Figure out the slope
+            if self.x1 > self.x2:
+                # right to left
+                lox = self.x2
+                hix = self.x1
+                loy = self.y2
+                hiy = self.y1
+            else:
+                lox = self.x1
+                hix = self.x2
+                loy = self.y1
+                hiy = self.y2
+            slope = float(hiy - loy) / float(hix - lox)
+            yf = float(loy)
+            for x in range(lox, hix + 1):
+                yield (x, int(yf))
+                yf += slope
+        else:
+            # No support for diagonals
+            return None
+
+
+def part1(segments: Sequence[Seg]):
+    # Create a counting dict, we can probably avoid the matrix stuff
+    points: DefaultDict[Tuple[int, int], int] = defaultdict(lambda: 0)
+    for seg in segments:
+        for point in seg.points(diag=False):
+            points[point] += 1
+    # Figure out how many locations where at least 2 lines overlap
+    count = len([overlap for overlap in points.values() if overlap > 1])
+    print(f"{count} overlaps >1")
+
+
+def part2(segments: Sequence[Seg]):
+    # Create a counting dict, we can probably avoid the matrix stuff
+    points: DefaultDict[Tuple[int, int], int] = defaultdict(lambda: 0)
+    for seg in segments:
+        for point in seg.points(diag=True):
+            points[point] += 1
+    # Figure out how many locations where at least 2 lines overlap
+    count = len([overlap for overlap in points.values() if overlap > 1])
+    print(f"{count} overlaps >1")
+
+
+segments = [Seg.from_str(line) for line in sys.stdin]
+print("Part 1")
+part1(segments)
+print("Part 2")
+part2(segments)