restructure, slow security solution

asecbadge_iter.py

@@ -0,0 +1,50 @@
+from collections import deque, defaultdict
+
+N, L, B = map(int, input().split())
+
+S, D = map(int, input().split())
+
+rooms = defaultdict(dict)
+
+bounds = set()
+
+for _ in range(L):
+    a, b, x, y = map(int, input().split())
+    rooms[a][b] = x, y + 1
+    bounds.add(x)
+    bounds.add(y + 1)
+
+total = 0
+
+bounds = sorted(bounds)
+
+
+def piecewise(seq):
+    it = iter(seq)
+    last = next(it)
+    for new in it:
+        yield last, new
+        last = new
+
+
+for a, b in piecewise(bounds):
+    q = deque([S])
+    visited = [0] * L
+
+    while q:
+        curr = q.pop()
+        visited[curr - 1] = 1
+        nbors = rooms[curr].items()
+
+        if curr == D:
+            total += b - a
+            break
+
+        for n, (la, lb) in nbors:
+            if visited[n - 1]:
+                continue
+
+            if a >= la and b <= lb:
+                q.append(n)
+
+print(total)