Fast and precise algorithms, with tests

vpn_manager/cidr4_merge/fast.py

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+from heapq import heapify, heappush, heappop
+from .util import mask, get_data, cidr4_to_node, make_cidr4
+
+
+def solution(cidrs, M):
+    h = []
+    d = {}
+    for ip, l in cidrs:
+        h.append((32-l, ip, l))
+        d[(ip, l)] = 0
+    heapify(h)
+    while len(h)>M:
+        x1, ip1, l1 = heappop(h)
+        x2, ip2, l2 = h[0]
+        if l1==l2 and ip1 & mask[l1-1] == ip2 & mask[l2-1]:
+            heappop(h)
+            if (ip1 & mask[l1-1], l1-1) not in d:
+                heappush(h, (x1+1, ip1 & mask[l1-1], l1-1))
+                d[(ip1 & mask[l1-1], l1-1)] = d[(ip1, l1)] + d[(ip2, l2)]
+            del d[(ip2, l2)]
+        else:
+            if (ip1 & mask[l1-1], l1-1) not in d:
+                heappush(h, (x1+1, ip1 & mask[l1-1], l1-1))
+                d[(ip1 & mask[l1-1], l1-1)] = d[(ip1, l1)] + 2**x1
+        del d[(ip1, l1)]
+        s = sum(d.values())
+        cidrs = list(d.keys())
+    return cidrs, s
+
+
+def main():
+    M = 20
+    a = get_data()
+    b = list(map(cidr4_to_node, a))
+    cidrs, s = solution(b, M)
+    cidrs = sorted([make_cidr4(*x) for x in cidrs])
+    print(cidrs, s, sep='\n')
+    
+
+if __name__=='__main__':
+    import cProfile
+    main()
+