Pavel Patsey
109 lines
3.0 KiB
Python
109 lines
3.0 KiB
Python
import cProfile
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Node = tuple[int, int]
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class Cidr4MergerError(Exception):
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pass
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def get_data(input_file):
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with open(input_file, "r") as file:
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data = file.read().splitlines()
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return data
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def cidr4_to_node(cidr4: str) -> Node:
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ip_address, mask_len = cidr4.strip().split("/")
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a, b, c, d = list(map(int, ip_address.split(".")))
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ip = a * 256**3 + b * 256**2 + c * 256**1 + d * 256**0
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mask_len = int(mask_len)
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return ip, mask_len
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def sort_nodes(nodes: list[Node]) -> list[Node]:
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return sorted(nodes)
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def find_parent(a: Node, b: Node) -> Node:
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ip_a, mask_len_a = a
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ip_b, mask_len_b = b
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mask_len = min(mask_len_a, mask_len_b)
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mask = ((1 << mask_len) - 1) << (32 - mask_len)
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while ip_a & mask != ip_b & mask:
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mask_len -= 1
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mask = (mask << 1) & ((1 << 32) - 1)
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ip = ip_a & mask
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parent_node = ip, mask_len
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if parent_node == a or parent_node == b:
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raise Cidr4MergerError(
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f"Error! Trying to find common parent of network and subnet! {parent_node=}, {a=}, {b=}."
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)
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return parent_node
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def calc_dip(mask_len_a: int, mask_len_b: int, mask_len_p: int) -> int:
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mask_len = mask_len_p + 1
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dip_a = 0
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while mask_len_a > mask_len:
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dip_a += 2 ** (32 - mask_len_a)
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mask_len_a -= 1
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dip_b = 0
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while mask_len_b > mask_len:
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dip_b += 2 ** (32 - mask_len_b)
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mask_len_b -= 1
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return dip_a + dip_b
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def merge_two_nodes(node_a: Node, node_b: Node) -> tuple[Node, int]:
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ip_a, mask_len_a = node_a
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ip_b, mask_len_b = node_b
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parent_node = find_parent(node_a, node_b)
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_, mask_len_p = parent_node
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dip = calc_dip(mask_len_a, mask_len_b, mask_len_p)
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return parent_node, dip
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def make_cidr4(ip, mask_len) -> str:
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lst = [str(ip >> (i << 3) & 0xFF) for i in reversed(range(4))]
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ip_address = ".".join(lst)
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return f"{ip_address}/{mask_len}"
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def merge_nodes(nodes: list[Node], required_len: int) -> tuple[list[Node], int]:
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sum_dip = 0
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while len(nodes) > required_len:
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min_tuple = None, (None, float("inf"))
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for i, (a, b) in enumerate(zip(nodes, nodes[1:])):
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parent_node, dip = merge_two_nodes(a, b)
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if dip < min_tuple[1][1]:
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min_tuple = i, (parent_node, dip)
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idx, (parent_node, dip) = min_tuple
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nodes = nodes[:idx] + [parent_node] + nodes[idx + 2 :]
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sum_dip += dip
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# for i, (a, b) in enumerate(zip(nodes, nodes[1:])):
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# parent_node, dip = merge_two_nodes(a, b)
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# assert parent_node != a
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# assert parent_node != b
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return nodes, sum_dip
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def main():
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file = "cidr4.txt"
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required_len = 20
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data = get_data(file)
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nodes = list(map(cidr4_to_node, data))
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nodes = sort_nodes(nodes)
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merged_nodes, sum_dip = merge_nodes(nodes, required_len)
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cidr4s = [make_cidr4(ip, mask_len) for ip, mask_len in merged_nodes]
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print(sorted(cidr4s), sum_dip, sep="\n")
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if __name__ == "__main__":
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cProfile.run("main()")
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