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54 lines
954 B
C++
54 lines
954 B
C++
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#include <iostream>
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using std::cin;
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using std::cout;
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const char endl = '\n';
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const int N = 5e6 + 5;
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int n, p, _k, k, a[N], b[N], s[N], ans;
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int binpow(int a, int b) {
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int res = 1;
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while (b) {
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if (b & 1) res = static_cast<long long>(res) * a % p;
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a = static_cast<long long>(a) * a % p;
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b >>= 1;
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}
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return res;
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}
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int main() {
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std::ios::sync_with_stdio(false);
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cin.tie(nullptr);
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cin >> n >> p >> _k;
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s[0] = 1;
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for (int i = 1; i <= n; i++) {
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cin >> a[i];
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s[i] = static_cast<long long>(s[i - 1]) * a[i] % p;
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}
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b[n + 1] = binpow(s[n], p - 2);
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for (int i = n; i; i--) {
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b[i] = static_cast<long long>(b[i + 1]) * a[i] % p;
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}
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k = _k;
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for (int i = 1; i <= n; i++) {
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ans = (ans + static_cast<long long>(s[i - 1]) * b[i + 1] % p * k) % p;
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k = static_cast<long long>(k) * _k % p;
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}
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cout << ans << endl;
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return 0;
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}
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