結果

問題 No.1212 Second Path
ユーザー lam6er
提出日時 2025-04-16 00:29:33
言語 PyPy3
(7.3.15)
結果
MLE  
実行時間 -
コード長 3,845 bytes
コンパイル時間 331 ms
コンパイル使用メモリ 82,476 KB
実行使用メモリ 516,644 KB
最終ジャッジ日時 2025-04-16 00:31:07
合計ジャッジ時間 10,312 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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ファイルパターン 結果
sample -- * 3
other MLE * 1 -- * 44
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 # 

import sys
from math import log2, ceil
from collections import defaultdict, deque

sys.setrecursionlimit(1 << 25)

def main():
    input = sys.stdin.read().split()
    ptr = 0
    N = int(input[ptr])
    ptr +=1
    edges = [[] for _ in range(N+1)]  # 1-based
    edge_set = defaultdict(set)
    for _ in range(N-1):
        u = int(input[ptr])
        v = int(input[ptr+1])
        w = int(input[ptr+2])
        ptr +=3
        edges[u].append((v, w))
        edges[v].append((u, w))
        edge_set[u].add((v, w))
        edge_set[v].add((u, w))
    LOG = ceil(log2(N)) if N >1 else 1
    parent = [[-1]*(N+1) for _ in range(LOG)]
    depth = [0]*(N+1)
    tin = [0]*(N+1)
    tout = [0]*(N+1)
    time = 0
    root = 1
    stack = [(root, -1, False)]
    adj = [[] for _ in range(N+1)]
    for u in range(1, N+1):
        for v, w in edges[u]:
            if v != parent[0][u]:
                adj[u].append((v, w))
    parent[0][root] = -1
    while stack:
        u, p, visited = stack.pop()
        if visited:
            tout[u] = time
            time +=1
            continue
        tin[u] = time
        time +=1
        parent[0][u] = p
        stack.append((u, p, True))
        for v, w in sorted(adj[u], key=lambda x: -x[0]):
            if v != p:
                depth[v] = depth[u] +1
                stack.append((v, u, False))
    for k in range(1, LOG):
        for v in range(1, N+1):
            if parent[k-1][v] != -1:
                parent[k][v] = parent[k-1][parent[k-1][v]]
    def lca(u, v):
        if depth[u] < depth[v]:
            u, v = v, u
        for k in reversed(range(LOG)):
            if depth[u] - (1<<k) >= depth[v]:
                u = parent[k][u]
        if u == v:
            return u
        for k in reversed(range(LOG)):
            if parent[k][u] != -1 and parent[k][u] != parent[k][v]:
                u = parent[k][u]
                v = parent[k][v]
        return parent[0][u]
    def is_ancestor(u, v):
        return tin[u] <= tin[v] and tout[u] >= tout[v]
    def get_path_up(u, a):
        path = []
        while u != a:
            path.append(u)
            u = parent[0][u]
        path.append(a)
        return path
    def get_path(u, v):
        a = lca(u, v)
        path_u = get_path_up(u, a)
        path_v = get_path_up(v, a)
        path_v.pop()
        return path_u + path_v[::-1]
    edge_info = []
    edge_to_idx = dict()
    original_edges = [dict() for _ in range(N+1)]
    for u in range(1, N+1):
        for v, w in edges[u]:
            original_edges[u][v] = w
    for u in range(1, N+1):
        edges[u].sort(key=lambda x: x[1])
    Q = int(input[ptr])
    ptr +=1
    for _ in range(Q):
        x = int(input[ptr])
        y = int(input[ptr+1])
        ptr +=2
        if x == y:
            print(-1)
            continue
        a = lca(x, y)
        path_nodes = []
        u = x
        while u != a:
            path_nodes.append(u)
            u = parent[0][u]
        path_nodes.append(a)
        tmp = []
        u = y
        while u != a:
            tmp.append(u)
            u = parent[0][u]
        path_nodes += tmp[::-1]
        S = 0
        path_edges = set()
        for i in range(len(path_nodes)-1):
            u = path_nodes[i]
            v = path_nodes[i+1]
            w = original_edges[u][v]
            S += w
            path_edges.add((u, v))
            path_edges.add((v, u))
        min_candidate = float('inf')
        for u in path_nodes:
            for v, w in edges[u]:
                if (u, v) not in path_edges and (v, u) not in path_edges:
                    if w < min_candidate:
                        min_candidate = w
                        break
        if min_candidate != float('inf'):
            print(S + 2 * min_candidate)
        else:
            print(-1)

if __name__ == "__main__":
    main()
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