init

AB.py

@@ -0,0 +1,37 @@
+import sys
+
+sys.setrecursionlimit(4000)
+
+data = sys.stdin.read().split()
+
+num_v = int(data[0])
+num_e = int(data[1])
+
+adj = [[] for _ in range(num_v + 1)]
+cursor = 2
+
+for _ in range(num_e):
+    src = int(data[cursor])
+    dst = int(data[cursor + 1])
+    cursor += 2
+    adj[src].append(dst)
+
+pairs = [0] * (num_v + 1)
+
+def find_match(node):
+    if visited[node]:
+        return False
+    visited[node] = True
+    for nxt in adj[node]:
+        if pairs[nxt] == 0 or find_match(pairs[nxt]):
+            pairs[nxt] = node
+            return True
+    return False
+
+total_matches = 0
+for start_node in range(1, num_v + 1):
+    visited = [False] * (num_v + 1)
+    if find_match(start_node):
+        total_matches += 1
+
+print(num_v - total_matches)