Submission #30117972

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Source Code Expand

n, m = map(int, input().split())
a = [0] * m
b = [0] * m
e = [[] for i in range(n)] # グラフの隣接リスト
for i in range(m):
    a[i], b[i] = map(int, input().split())
    a[i] -= 1
    b[i] -= 1
    e[a[i]].append(b[i])
    e[b[i]].append(a[i])
answer = 0
for i in range(m): # 辺 i を削除
    visited = [0] * n
    def dfs(v):
        global visited
        visited[v] = 1
        for u in e[v]:
            if {v, u} == {a[i], b[i]}: # 順序のない集合として比較
                continue # 削除された辺は使わない
            if visited[u] == 0:
                dfs(u)
    dfs(0)
    if sum(visited) < n: # すべての頂点を訪問できなかったとき
        answer += 1
print(answer)

Submission Info

Judge Result