結果

問題 No.1553 Lovely City
ユーザー neterukunneterukun
提出日時 2021-06-18 21:49:03
言語 PyPy3
(7.3.15)
結果
AC  
実行時間 1,582 ms / 2,000 ms
コード長 3,551 bytes
コンパイル時間 538 ms
コンパイル使用メモリ 82,304 KB
実行使用メモリ 242,076 KB
最終ジャッジ日時 2024-06-22 20:12:26
合計ジャッジ時間 32,313 ms
ジャッジサーバーID
（参考情報） 		judge1 / judge5
このコードへのチャレンジ
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テストケース

テストケース表示
入力 結果 実行時間
実行使用メモリ
testcase_00 AC 38 ms
53,376 KB
testcase_01 AC 39 ms
53,504 KB
testcase_02 AC 350 ms
162,808 KB
testcase_03 AC 47 ms
56,536 KB
testcase_04 AC 50 ms
57,856 KB
testcase_05 AC 61 ms
67,840 KB
testcase_06 AC 68 ms
67,200 KB
testcase_07 AC 51 ms
62,080 KB
testcase_08 AC 1,096 ms
165,424 KB
testcase_09 AC 1,128 ms
167,816 KB
testcase_10 AC 1,266 ms
197,940 KB
testcase_11 AC 997 ms
164,284 KB
testcase_12 AC 1,207 ms
200,444 KB
testcase_13 AC 969 ms
159,112 KB
testcase_14 AC 1,107 ms
175,976 KB
testcase_15 AC 1,069 ms
175,664 KB
testcase_16 AC 1,208 ms
172,164 KB
testcase_17 AC 1,023 ms
166,580 KB
testcase_18 AC 1,543 ms
234,936 KB
testcase_19 AC 1,582 ms
234,640 KB
testcase_20 AC 1,525 ms
225,456 KB
testcase_21 AC 1,558 ms
232,952 KB
testcase_22 AC 1,566 ms
241,480 KB
testcase_23 AC 1,556 ms
241,016 KB
testcase_24 AC 1,526 ms
242,076 KB
testcase_25 AC 1,530 ms
227,732 KB
testcase_26 AC 1,512 ms
232,852 KB
testcase_27 AC 1,560 ms
220,488 KB
権限があれば一括ダウンロードができます

ソースコード

diff # 

class UnionFind:
    def __init__(self, n):
        self.parent = [-1] * n
        self.n = n
        self.cnt = n

    def root(self, x):
        if self.parent[x] < 0:
            return x
        else:
            self.parent[x] = self.root(self.parent[x])
            return self.parent[x]

    def merge(self, x, y):
        x = self.root(x)
        y = self.root(y)
        if x == y:
            return False
        if self.parent[x] > self.parent[y]:
            x, y = y, x
        self.parent[x] += self.parent[y]
        self.parent[y] = x
        self.cnt -= 1
        return True

    def same(self, x, y):
        return self.root(x) == self.root(y)

    def size(self, x):
        return -self.parent[self.root(x)]

    def count(self):
        return self.cnt

    def groups(self):
        res = [[] for _ in range(self.n)]
        for i in range(self.n):
            res[self.root(i)].append(i)
        return [group for group in res if group]


class StronglyConnectedComponents:
    def __init__(self, n):
        self.n = n
        self.graph = [[] for _ in range(n)]
        self.rev_graph = [[] for _ in range(n)]
        self.labels = [-1] * n
        self.lb_cnt = 0

    def add_edge(self, v, nxt_v):
        self.graph[v].append(nxt_v)
        self.rev_graph[nxt_v].append(v)

    def build(self):
        self.post_order = []
        self.used = [False] * self.n
        for v in range(self.n):
            if not self.used[v]:
                self._dfs(v)

        for v in reversed(self.post_order):
            if self.labels[v] == -1:
                self._rev_dfs(v)
                self.lb_cnt += 1

    def _dfs(self, v):
        stack = [v, 0]
        while stack:
            v, idx = stack[-2:]
            if not idx and self.used[v]:
                stack.pop()
                stack.pop()
            else:
                self.used[v] = True
                if idx < len(self.graph[v]):
                    stack[-1] += 1
                    stack.append(self.graph[v][idx])
                    stack.append(0)
                else:
                    stack.pop()
                    self.post_order.append(stack.pop())

    def _rev_dfs(self, v):
        stack = [v]
        self.labels[v] = self.lb_cnt
        while stack:
            v = stack.pop()
            for nxt_v in self.rev_graph[v]:
                if self.labels[nxt_v] != -1:
                    continue
                stack.append(nxt_v)
                self.labels[nxt_v] = self.lb_cnt

    def construct_dag(self):
        self.dag = [[] for i in range(self.lb_cnt)]
        self.groups = [[] for i in range(self.lb_cnt)]
        for v, lb in enumerate(self.labels):
            for nxt_v in self.graph[v]:
                nxt_lb = self.labels[nxt_v]
                if lb == nxt_lb:
                    continue
                self.dag[lb].append(nxt_lb)
            self.groups[lb].append(v)
        return self.dag, self.groups


n, m = map(int, input().split())
edges = [list(map(int, input().split())) for i in range(m)]

    
scc = StronglyConnectedComponents(n)
uf = UnionFind(n)
for u, v in edges:
    u -= 1
    v -= 1
    scc.add_edge(u, v)
    uf.merge(u, v)

scc.build()
dag, group = scc.construct_dag()


ans = []
for gp in uf.groups():
    gp = sorted(gp, key=lambda x: scc.labels[x])
    lb = [scc.labels[i] for i in gp]
    for i in range(len(gp) - 1):
        ans.append((gp[i], gp[i + 1]))
    if len(set(lb)) != len(lb):
        ans.append((gp[-1], gp[0]))

print(len(ans))
for u, v in ans:
    print(u + 1, v + 1)
0