結果

問題 No.1212 Second Path
コンテスト
ユーザー gew1fw
提出日時 2025-06-12 21:35:06
言語 PyPy3
(7.3.15)
結果
TLE  
実行時間 -
コード長 3,042 bytes
コンパイル時間 360 ms
コンパイル使用メモリ 81,664 KB
実行使用メモリ 358,084 KB
最終ジャッジ日時 2025-06-12 21:37:17
合計ジャッジ時間 12,980 ms
ジャッジサーバーID
（参考情報） 		judge2 / judge4
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ファイルパターン 結果
sample -- * 3
other TLE * 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 #
raw source code 

import sys
from collections import defaultdict, deque

def main():
    sys.setrecursionlimit(1 << 25)
    input = sys.stdin.read().split()
    ptr = 0
    N = int(input[ptr])
    ptr += 1

    edges = []
    adj = defaultdict(list)
    for _ in range(N-1):
        u = int(input[ptr])
        v = int(input[ptr+1])
        w = int(input[ptr+2])
        ptr +=3
        edges.append((u, v, w))
        adj[u].append((v, w))
        adj[v].append((u, w))

    for u in adj:
        adj[u].sort(key=lambda x: x[1])

    LOG = 20
    parent = [[-1]*(N+1) for _ in range(LOG)]
    depth = [0]*(N+1)
    dist_root = [0]*(N+1)

    root = 1
    stack = [(root, -1, 0, 0)]
    while stack:
        u, p, d, cost = stack.pop()
        parent[0][u] = p
        depth[u] = d
        dist_root[u] = cost
        for v, w in adj[u]:
            if v != p:
                stack.append((v, u, d+1, cost + w))

    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 range(LOG-1, -1, -1):
            if depth[u] - (1 << k) >= depth[v]:
                u = parent[k][u]
        if u == v:
            return u
        for k in range(LOG-1, -1, -1):
            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 get_path(u, lca_node):
        path = []
        while u != lca_node:
            for v, w in adj[u]:
                if v == parent[0][u]:
                    path.append((u, v, w))
                    u = v
                    break
        return path

    def get_path_edges(u, v):
        ancestor = lca(u, v)
        path_u = get_path(u, ancestor)
        path_v = get_path(v, ancestor)
        return path_u + path_v[::-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(0)
            continue

        path_edges = get_path_edges(x, y)
        edge_set = set()
        for u, v, w in path_edges:
            if u < v:
                edge_set.add((u, v))
            else:
                edge_set.add((v, u))

        sum_s = sum(w for u, v, w in path_edges)
        min_detour = None

        path_nodes = set()
        for u, v, _ in path_edges:
            path_nodes.add(u)
            path_nodes.add(v)

        for u in path_nodes:
            for v, w in adj[u]:
                edge_tuple = (u, v) if u < v else (v, u)
                if edge_tuple not in edge_set:
                    if min_detour is None or w < min_detour:
                        min_detour = w
                    break  # since edges are sorted, first non-path edge is minimal

        if min_detour is not None:
            print(sum_s + 2 * min_detour)
        else:
            print(-1)

if __name__ == '__main__':
    main()
0