107 lines
2.2 KiB
C++
107 lines
2.2 KiB
C++
#include <iostream>
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#include <cstring>
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#include <queue>
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#include <cstdio>
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using namespace std;
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const int MAX = 510000;
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int pre[MAX], cnt[MAX];
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int isleaf[MAX];
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queue<int> q;
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long long n, mod;
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int prime[MAX], num_prime, cprime[MAX], isprime[MAX];
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void init()
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{
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scanf("%d%d", &n, &mod);
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pre[1] = -1;
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memset(isleaf, 0, sizeof(isleaf));
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for (int i = 2; i <= n; i++)
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{
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scanf("%d", &pre[i]);
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isleaf[pre[i]]++;
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}
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for (int i = 1; i <= n; i++)
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if (!isleaf[i])
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q.push(i);
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}
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void bfs()
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{
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for (int i = 1; i <= n; i++)
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cnt[i] = 1;
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while (!q.empty())
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{
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int u = q.front();
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q.pop();
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if (u == 1)
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continue;
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cnt[pre[u]] += cnt[u];
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isleaf[pre[u]]--;
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if (!isleaf[pre[u]])
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q.push(pre[u]);
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}
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}
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void prime_init()
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{
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memset(isprime, 1, sizeof(isprime));
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int cnt = 0;
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isprime[0] = isprime[1] = -1;
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for (int i = 2; i < MAX; i++)
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if (isprime[i] != -1)
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{
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isprime[i] = cnt++;
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for (int j = 2; j * i < MAX; j++)
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isprime[i * j] = -1;
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}
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num_prime = 0;
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for (int i = 2; i <= MAX; i++)
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if (isprime[i] != -1)
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prime[num_prime++] = i;
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}
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void fac(int a, int v)
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{
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for (int i = 0; a != 1; i++)
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{
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while (a % prime[i] == 0)
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cprime[i] += v, a /= prime[i];
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if (isprime[a] != -1)
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cprime[isprime[a]] += v, a = 1;
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}
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}
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long long pow(int a, int b)
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{
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long long x = a, r = 1;
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while (b)
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{
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if (b & 1)
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r = (r * x) % mod;
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x = (x * x) % mod;
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b >>= 1;
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}
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return r;
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}
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long long solve()
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{
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memset(cprime, 0, sizeof(cprime));
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for (int i = 2; i < n; i++)
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fac(i, 1);
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for (int i = 2; i <= n; i++)
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fac(cnt[i], -1);
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long long res = 1;
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for (int i = 0; i <= n && res != 0; i++)
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if (cprime[i])
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res = (res * pow(prime[i], cprime[i])) % mod;
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return res;
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}
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int main()
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{
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prime_init();
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int t;
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scanf("%d", &t);
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while (t--)
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{
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init();
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bfs();
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cout << solve() << endl;
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}
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return 0;
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}
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