Day 3

2019/day3.py

@@ -0,0 +1,75 @@
+import re
+
+EX0 = ["R8,U5,L5,D3", "U7,R6,D4,L4"]
+EX1 = ["R75,D30,R83,U83,L12,D49,R71,U7,L72", "U62,R66,U55,R34,D71,R55,D58,R83"]
+EX2 = ["R98,U47,R26,D63,R33,U87,L62,D20,R33,U53,R51", "U98,R91,D20,R16,D67,R40,U7,R15,U6,R7"]
+
+def main():
+    with open("day3.txt", "rt") as input_file:
+        lines = list(input_file.readlines())
+    solve(lines)
+
+def solve(input_lines):
+    wires = [(wire_id, line.strip().split(",")) for wire_id, line in enumerate(input_lines)]
+    grid = compute_grid(wires)
+    intersections = get_intersections(grid)
+    # print("Intersections:", intersections)
+    distances = get_manhattan_distances(intersections)
+    # print("Distances:", distances)
+    print("Min:", min(distances))
+
+def compute_grid(wires):
+    grid = {}
+    for wire_id, codes in wires:
+        fill_grid(wire_id, codes, grid)
+    return grid
+
+CODE_RE = re.compile(r"(\w)(\d+)")
+
+def fill_grid(wire_id, codes, grid):
+    x = 0
+    y = 0
+    for code in codes:
+        match = CODE_RE.match(code)
+        op, arg = match.groups()
+        for _ in range(int(arg)):
+            if op == "R":
+                y += 1
+            elif op == "L":
+                y -= 1
+            elif op == "U":
+                x += 1
+            elif op == "D":
+                x -= 1
+            inc_point((x, y), grid, wire_id)
+
+def inc_point(point, grid, wire_id):
+    x, y = point
+    if x not in grid:
+        grid[x] = {}
+    if y not in grid[x]:
+        grid[x][y] = [wire_id]
+    elif wire_id not in grid[x][y]:
+        grid[x][y].append(wire_id)
+
+def get_intersections(grid):
+    intersections = []
+    for x, line in grid.items():
+        for y, wire_ids in line.items():
+            if len(wire_ids) > 1:
+                intersections.append((x, y))
+    return intersections
+
+def get_manhattan_distances(points):
+    distances = []
+    for point in points:
+        distances.append(manhattan_dist((0, 0), point))
+    return distances
+
+def manhattan_dist(p1, p2):
+    p1x, p1y = p1
+    p2x, p2y = p2
+    return abs(p1x - p2x) + abs(p1y - p2y)
+
+if __name__ == "__main__":
+    main()