"""# ### 谜题描述 Emuskald considers himself a master of flow algorithms. Now he has completed his most ingenious program yet — it calculates the maximum flow in an undirected graph. The graph consists of n vertices and m edges. Vertices are numbered from 1 to n. Vertices 1 and n being the source and the sink respectively. However, his max-flow algorithm seems to have a little flaw — it only finds the flow volume for each edge, but not its direction. Help him find for each edge the direction of the flow through this edges. Note, that the resulting flow should be correct maximum flow. More formally. You are given an undirected graph. For each it's undirected edge (ai, bi) you are given the flow volume ci. You should direct all edges in such way that the following conditions hold: 1. for each vertex v (1 < v < n), sum of ci of incoming edges is equal to the sum of ci of outcoming edges; 2. vertex with number 1 has no incoming edges; 3. the obtained directed graph does not have cycles. Input The first line of input contains two space-separated integers n and m (2 ≤ n ≤ 2·105, n - 1 ≤ m ≤ 2·105), the number of vertices and edges in the graph. The following m lines contain three space-separated integers ai, bi and ci (1 ≤ ai, bi ≤ n, ai ≠ bi, 1 ≤ ci ≤ 104), which means that there is an undirected edge from ai to bi with flow volume ci. It is guaranteed that there are no two edges connecting the same vertices; the given graph is connected; a solution always exists. Output Output m lines, each containing one integer di, which should be 0 if the direction of the i-th edge is ai → bi (the flow goes from vertex ai to vertex bi) and should be 1 otherwise. The edges are numbered from 1 to m in the order they are given in the input. If there are several solutions you can print any of them. Examples Input 3 3 3 2 10 1 2 10 3 1 5 Output 1 0 1 Input 4 5 1 2 10 1 3 10 2 3 5 4 2 15 3 4 5 Output 0 0 1 1 0 Note In the first test case, 10 flow units pass through path , and 5 flow units pass directly from source to sink: . Here is a reference code to solve this task. You can use this to help you genereate cases or validate the solution. ```python #include using namespace std; const int maxm = 200000 + 5; const int maxn = 200000 + 5; struct Edge { int from, to, w, id; }; vector edges; vector G[maxn]; int ans[maxm]; int n, m; int win[maxn], wall[maxn]; inline void solve() { memset(ans, -1, sizeof ans); queue Q; Q.push(1); while (!Q.empty()) { int now = Q.front(); Q.pop(); vector tocheck; for (const int& i : G[now]) { Edge& e = edges[i]; if (ans[e.id] != -1) continue; int to; if (now == e.from) to = e.to, ans[e.id] = 0; else to = e.from, ans[e.id] = 1; win[to] += e.w; wall[to] -= e.w; if (to != n) tocheck.push_back(to); } for (const int& nx : tocheck) if (win[nx] == wall[nx]) Q.push(nx); } } int main() { scanf(\"%d%d\", &n, &m); for (int i = 0, a, b, c; i < m; i++) { scanf(\"%d%d%d\", &a, &b, &c); edges.push_back((Edge){a, b, c, i}); G[a].push_back((int)edges.size() - 1); G[b].push_back((int)edges.size() - 1); wall[a] += c; wall[b] += c; } solve(); for (int i = 0; i < m; i++) printf(\"%d\n\", ans[i]); } ``` 请完成上述谜题的训练场环境类实现,包括所有必要的方法。 """ from bootcamp import Basebootcamp import random from collections import defaultdict, deque from bootcamp import Basebootcamp class Edge: def __init__(self, from_, to_, w_, id_): self.from_ = from_ self.to_ = to_ self.w_ = w_ self.id_ = id_ class Cflawedflowbootcamp(Basebootcamp): def __init__(self, max_n=8, max_m=15): self.max_n = max_n self.max_m = max_m def case_generator(self): n = random.randint(2, self.max_n) max_edges = n * (n - 1) // 2 m = random.randint(n-1, min(max_edges, self.max_m)) edges = self._generate_connected_edges(n, m) solution = self._generate_solution(n, edges) return { "n": n, "m": m, "edges": edges, "solution": solution } @staticmethod def _generate_connected_edges(n, m): parent = list(range(n+1)) def find(u): if parent[u] != u: parent[u] = find(parent[u]) return parent[u] edges = [] existing = set() # Generate spanning tree to ensure connectivity nodes = list(range(1, n+1)) random.shuffle(nodes) root = nodes[0] for node in nodes[1:]: a, b = root, node if a > b: a, b = b, a c = random.randint(1, 10000) edges.append((a, b, c)) existing.add((a, b)) parent[b] = a # Add remaining edges remaining = m - (n-1) candidates = [(i, j) for i in range(1, n+1) for j in range(i+1, n+1) if (i, j) not in existing] while remaining > 0 and candidates: add_num = min(remaining, len(candidates)) selected = random.sample(candidates, add_num) for a, b in selected: c = random.randint(1, 10000) edges.append((a, b, c)) existing.add((a, b)) candidates.remove((a, b)) # Prevent duplicate selection remaining -= add_num random.shuffle(edges) return edges[:m] @staticmethod def _generate_solution(n, edges): m = len(edges) graph = [[] for _ in range(n+1)] wall = [0]*(n+1) for idx, (a, b, c) in enumerate(edges): edge = Edge(a, b, c, idx) graph[a].append(edge) graph[b].append(edge) wall[a] += c wall[b] += c ans = [-1]*m win = [0]*(n+1) q = deque([1]) while q: u = q.popleft() to_check = [] for edge in graph[u]: if ans[edge.id_] != -1: continue if edge.from_ == u: v = edge.to_ ans[edge.id_] = 0 else: v = edge.from_ ans[edge.id_] = 1 win[v] += edge.w_ wall[v] -= edge.w_ if v != n: to_check.append(v) for v in to_check: if win[v] == wall[v]: q.append(v) return ans @staticmethod def prompt_func(question_case): edges = question_case["edges"] n = question_case["n"] m = question_case["m"] edge_lines = "\n".join([f"{a} {b} {c}" for a, b, c in edges]) return f"""作为流量算法专家,请确定无向图中各边方向,并遵守以下规则: 1. 源点(1号顶点)没有入边 2. 中间节点(非源点和汇点)流入等于流出 3. 最终图必须无环 输入格式: {n} {m} {edge_lines} 请输出{m}个0或1(对应每条边的方向),答案用[answer]标签包裹,如: [answer] 0 1 1 0 [/answer]""" @staticmethod def extract_output(output): import re matches = re.findall(r'\[answer\](.*?)\[/answer\]', output, re.DOTALL) if not matches: return None digits = re.findall(r'\b[01]\b', matches[-1]) return [int(d) for d in digits] if digits and len(digits) == len(matches[-1].split()) else None @classmethod def _verify_correction(cls, solution, identity): if len(solution) != identity["m"]: return False edges = identity["edges"] n = identity["n"] # Check source has no incoming edges for (a, b, _), d in zip(edges, solution): if (d == 0 and b == 1) or (d == 1 and a == 1): return False # Flow conservation check inflow = defaultdict(int) outflow = defaultdict(int) for (a, b, c), d in zip(edges, solution): if d == 0: outflow[a] += c inflow[b] += c else: outflow[b] += c inflow[a] += c for v in range(2, n): if inflow.get(v, 0) != outflow.get(v, 0): return False # Acyclicity check with topological sort adj = [[] for _ in range(n+1)] in_degree = [0]*(n+1) for (a, b, _), d in zip(edges, solution): u, v = (a, b) if d == 0 else (b, a) adj[u].append(v) in_degree[v] += 1 q = deque([u for u in range(1, n+1) if in_degree[u] == 0]) visited = 0 while q: u = q.popleft() visited += 1 for v in adj[u]: in_degree[v] -= 1 if in_degree[v] == 0: q.append(v) return visited == n # All nodes must be visited for acyclic graph