21 lines
516 B
C++
21 lines
516 B
C++
constexpr int N = 3e6 + 10;
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ll fact[N], factrev[N + 1], s[N + 1];
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void prep() {
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fact[0] = factrev[0] = 1;
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for (int i = 1; i < N; ++i) {
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fact[i] = (fact[i - 1] * i) % MDL;
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}
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s[0] = 1;
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for (int i = 1; i <= N; ++i) {
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s[i] = s[i - 1] * fact[i - 1] % MDL;
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}
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factrev[N] = inverse(s[N], MDL);
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for (int i = N; i; --i) {
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factrev[i - 1] = factrev[i] * fact[i - 1] % MDL;
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}
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for (int i = 0; i < N; ++i) {
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factrev[i] = factrev[i + 1] * s[i] % MDL;
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}
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}
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