Company Queries II

import sys

sys.setrecursionlimit(10**7)
input = sys.stdin.readline

n, q = map(int, input().split())
boss = [0] + [0] + list(map(int, input().split()))

adj = [[] for _ in range(n + 1)]
for i in range(2, n + 1):
    adj[boss[i]].append(i)

LOG = 20  # ~ log2(2*10^5)
up = [[0] * (n + 1) for _ in range(LOG)]
depth = [0] * (n + 1)


def dfs(u, p):
    up[0][u] = p
    for i in range(1, LOG):
        up[i][u] = up[i - 1][up[i - 1][u]]
    for v in adj[u]:
        if v != p:
            depth[v] = depth[u] + 1
            dfs(v, u)


dfs(1, 0)


def lca(a, b):
    if depth[a] < depth[b]:
        a, b = b, a
    # Lift a up to depth[b]
    diff = depth[a] - depth[b]
    for i in range(LOG):
        if diff & (1 << i):
            a = up[i][a]

    if a == b:
        return a

    # Lift both up until their ancestors differ
    for i in reversed(range(LOG)):
        if up[i][a] != up[i][b]:
            a = up[i][a]
            b = up[i][b]

    return up[0][a]


for _ in range(q):
    a, b = map(int, input().split())
    print(lca(a, b))

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: TIME LIMIT EXCEEDED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: TIME LIMIT EXCEEDED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: TIME LIMIT EXCEEDED