結果
問題 | No.754 畳み込みの和 |
ユーザー | popofy |
提出日時 | 2023-10-09 00:38:34 |
言語 | C++23 (gcc 12.3.0 + boost 1.83.0) |
結果 |
AC
|
実行時間 | 223 ms / 5,000 ms |
コード長 | 20,425 bytes |
コンパイル時間 | 2,845 ms |
コンパイル使用メモリ | 218,740 KB |
実行使用メモリ | 18,524 KB |
最終ジャッジ日時 | 2024-07-26 18:18:12 |
合計ジャッジ時間 | 4,790 ms |
ジャッジサーバーID (参考情報) |
judge4 / judge5 |
(要ログイン)
テストケース
テストケース表示入力 | 結果 | 実行時間 実行使用メモリ |
---|---|---|
testcase_00 | AC | 223 ms
18,472 KB |
testcase_01 | AC | 219 ms
18,396 KB |
testcase_02 | AC | 220 ms
18,524 KB |
ソースコード
// #define Q__OPTIMIZE // #define Q__INCLUDE_ATCODER_LIB // #define Q__INTERACTIVE #if !__INCLUDE_LEVEL__ #include __FILE__ struct Solver { void solve() { INT(n); VEC(ll,a,n+1); VEC(ll,b,n+1); Polynomial<ll> P,Q; P.coef = a; Q.coef = b; auto C = P * Q; DUMP(C.coef); ll ans = 0; REP(i,n+1) ans = safe_mod(ans+C[i],MOD); print(ans); } void naive() { } } solver; signed main(void){ NO_SYNC_STD; V<string> options; #ifdef Q__OPTIMIZE options.push_back("OPTIMIZE"); #endif #ifdef Q__INTERACTIVE options.push_back("INTERACTIVE"); #endif #ifdef Q__INCLUDE_ATCODER_LIB options.push_back("INCLUDE_ATCODER_LIB"); #endif DUMP(options); #ifndef Q__NAIVE solver.solve(); #else DUMP("naive"); solver.naive(); #endif return 0; } #else #define _GLIBCXX_DEQUE_BUF_SIZE 64 #ifdef Q__OPTIMIZE #pragma GCC target("avx") #pragma GCC optimize("O3") #pragma GCC optimize("unroll-loops") #endif #include <algorithm> #include <array> #include <bitset> #include <cassert> #include <chrono> #include <cmath> #include <complex> #include <deque> #include <forward_list> #include <fstream> #include <functional> #include <iomanip> #include <ios> #include <iostream> #include <limits> #include <list> #include <map> #include <memory> #include <numeric> #include <optional> #include <queue> #include <random> #include <set> #include <sstream> #include <stack> #include <string> #include <thread> #include <tuple> #include <type_traits> #include <unordered_map> #include <unordered_set> #include <utility> #include <vector> #ifdef Q__INCLUDE_ATCODER_LIB #include <atcoder/all> using namespace atcoder; //using mint = modint1000000007; using mint = modint998244353; std::istream &operator>>(std::istream& is, mint& a) { long long tmp; is >> tmp; a = tmp; return is; } std::ostream &operator<<(std::ostream& os, const mint& a) {os << a.val(); return os;} #endif using namespace std; #define MOD 1000000007 #define OVERLOAD4(a, b, c, d, e, ...) e #define REP1(a) for(decltype(a) i = 0, i##_len = (a); i < i##_len; ++i) #define REP2(i, a) for(decltype(a) i = 0, i##_len = (a); i < i##_len; ++i) #define REP3(i, a, b) for(decltype(b) i = (a), i##_len = (b); i < i##_len; ++i) #define REP4(i, a, b, c) for(decltype(b) i = (a), i##_len = (b); i < i##_len; i += (c)) #define REP(...) OVERLOAD4(__VA_ARGS__, REP4, REP3, REP2, REP1)(__VA_ARGS__) #define RREP1(a) for(decltype(a) i = (a); i--;) #define RREP2(i, a) for(decltype(a) i = (a); i--;) #define RREP3(i, a, b) for(decltype(a) i = (b), i##_len = (a); i-- > i##_len;) #define RREP4(i, a, b, c) for(decltype(a) i = (a)+((b)-(a)-1)/(c)*(c), i##_len = (a); i >= i##_len; i -= c) #define RREP(...) OVERLOAD4(__VA_ARGS__, RREP4, RREP3, RREP2, RREP1)(__VA_ARGS__) #define MREP(v,...) for(auto v:make_enum_vec({__VA_ARGS__})) #define QREP(q, l, r, n) for (ll q = 1, l = n / (q + 1) + 1, r = n / q + 1; q <= n; q = (q == n ? n + 1 : n / (n / (q + 1))), l = n / (q + 1) + 1, r = n / q + 1) #define COMB_REP(i,n,k) for (ll t, i = POW2(k) - 1; i < POW2(n); t=i|(i-1), i = (t+1)|(((~t & - ~t)-1) >> (__builtin_ctzll(i)+1))) #define SUBSET_ENUM_REP(i,s) for (ll i = (1LL << 60) - 1; i >= 0, i &= s; --i) #define SUBSET_INCLUDE_REP(i,n,s) for (int i = s; i < POW2(n); i=(++i)|s) #define POPONLY_REP(i,s) for (ll i=s&-s; i; i=s&(~s+(i << 1))) #define ALL(x) (x).begin(), (x).end() #define RALL(x) (x).rbegin(), (x).rend() #define SZ(x) ((int)(x).size()) #define POW2(n) (1LL << ((int)(n))) #define GET1BIT(x,n) (((x) >> (int)(n)) & 1) #define INF ((1 << 30) - 1) #define INFL (1LL << 60) #define PRECISION std::setprecision(16) #define SLEEP(n) std::this_thread::sleep_for(std::chrono::seconds(n)) #define INT(...) int __VA_ARGS__; input(__VA_ARGS__) #define LL(...) ll __VA_ARGS__; input(__VA_ARGS__) #define STR(...) string __VA_ARGS__; input(__VA_ARGS__) #define LD(...) ld __VA_ARGS__; input(__VA_ARGS__) #define VEC(type, name, size) vector<type> name(size); input(name) #ifdef Q__INTERACTIVE #define NO_SYNC_STD #define ENDL std::endl #else #define NO_SYNC_STD std::cin.tie(nullptr);ios::sync_with_stdio(false) #define ENDL "\n" #endif #ifdef Q__LOCAL #include <dump.hpp> #define DUMP(...) DUMPOUT << " " << string(#__VA_ARGS__) << ": " << "[" << to_string(__LINE__) << ":" << __FUNCTION__ << "]" << endl ,dump_func(__VA_ARGS__) #define VDUMP(...) DUMPOUT << " " << string(#__VA_ARGS__) << ": " << "[" << to_string(__LINE__) << ":" << __FUNCTION__ << "]" << endl, vdump_func(__VA_ARGS__) #else #define DUMP(...) #define VDUMP(...) #endif using ll=long long; using ull=unsigned long long; using ld=long double; template<class T> using V=vector<T>; template<class T> using VV=vector<vector<T>>; template<class T> using PQ=priority_queue<T,V<T>,greater<T>>; template<class T> istream &operator>>(istream &is,V<T> &v){for(auto&& e:v)is >> e;return is;} template<class T> istream &operator>>(istream &is,complex<T> &v){T x,y; is >> x >> y;v.real(x);v.imag(y);return is;} template<class T,class U> istream &operator>>(istream &is,pair<T,U> &v){is >> v.first >> v.second;return is;} template<class T,size_t n> istream &operator>>(istream &is,array<T,n> &v){for(auto&& e:v)is >> e;return is;} template<class... A> void input(A&&... args){(cin >> ... >> args);} template<class... A> void print_rest(){cout << ENDL;} template<class T,class... A> void print_rest(const T& first,const A&... rest){cout << " " << first;print_rest(rest...);} template<class T,class... A> void print(const T& first,const A&... rest){cout << fixed << PRECISION << first;print_rest(rest...);} template<class T,class... A> void die(const T& first,const A&... rest){cout << fixed << PRECISION << first;print_rest(rest...);exit(0);} template <typename ... Args> string fmt(const string& fmt, Args ... args ){size_t len = snprintf( nullptr, 0, fmt.c_str(), args ... );vector<char> buf(len + 1);snprintf(&buf[0], len + 1, fmt.c_str(), args ... );return string(&buf[0], &buf[0] + len);} template<class T> inline string join(const T& v,string sep=" "){if(!SZ(v))return "";stringstream ss;for(auto&& e:v)ss << sep << e;return ss.str().substr(SZ(sep));} V<string> split(const string &s,char sep=' ') {V<string> ret;stringstream ss(s);string buf;while(getline(ss,buf,sep))ret.push_back(buf);return ret;} template<class T> inline string padding(const T& v,int len,char pad=' ',bool l=false){stringstream ss;ss << (l?std::left:std::right) << setw(len) << setfill(pad) << v;return ss.str();} template<class T> V<T> make_vec(size_t n,T a){return V<T>(n,a);} template<class... Ts> auto make_vec(size_t n,Ts... ts){return V<decltype(make_vec(ts...))>(n,make_vec(ts...));} template<class T> inline bool chmax(T& a,T b){if(a<b){a=b;return 1;} return 0;} template<class T> inline bool chmin(T& a,T b){if(a>b){a=b;return 1;} return 0;} template<class T,class F> pair<T,T> binarysearch(T ng,T ok,T eps,F f,bool sign=false){while(abs(ng-ok)>eps){auto mid=ng+(ok-ng)/2;if(sign^f(mid)){ok=mid;}else{ng=mid;}}return{ng,ok};} template<class T> constexpr T cdiv(T x,T y){return (x+y-1)/y;} template<class T> constexpr bool between(T a,T x,T b){return(a<=x&&x<b);} template<class T> constexpr T pos1d(T y,T x,T h,T w){assert(between(T(0),y,h));assert(between(T(0),x,w));return y*w+x;} template<class T> constexpr pair<T,T> pos2d(T p,T h,T w){T y=p/w,x=p-y*w;assert(between(T(0),y,h));assert(between(T(0),x,w));return{y,x};} template<class T> constexpr T sign(T n) {return (n > 0) - (n < 0);} template<class T> inline V<T> transposed(V<T>& A){int h=SZ(A),w=SZ(A[0]);V<T> tA(w);REP(i,h)REP(j,w)tA[j].push_back(A[i][j]);return tA;} template<class T> inline V<T> ruiseki(V<T>& a){auto ret = a; ret.push_back(T(0));exclusive_scan(ALL(ret), ret.begin(), 0);return ret;} template<class T> inline V<T> kaisa(V<T>& a){V<T> ret(a.size());adjacent_difference(ALL(a), ret.begin());return ret;} template<class T> inline int g_index(V<T> &s, T x) { if (s.empty()) return -2; auto it = upper_bound(ALL(s), x); if (it == s.end()) return -1; return (int)distance(s.begin(), it); } template<class T> inline int ge_index(V<T> &s, T x) { if (s.empty()) return -2; auto it = lower_bound(ALL(s), x); if (it == s.end()) return -1; return (int)distance(s.begin(), it); } template<class T> inline int l_index(V<T> &s, T x) { if (s.empty()) return -2; auto it = lower_bound(ALL(s), x); if (it == s.begin()) return -1; return (int)distance(s.begin(), prev(it)); } template<class T> inline int le_index(V<T> &s, T x) { if (s.empty()) return -2; auto it = upper_bound(ALL(s), x); if (it == s.begin()) return -1; return (int)distance(s.begin(), prev(it)); } template<class T> inline pair<typename set<T>::iterator,bool> g_it(set<T> &s, T x) { if (s.empty()) return {s.end(), false}; auto it = s.upper_bound(x); if (it == s.end()) return {it, false}; return {it, true}; } template<class T> inline pair<typename set<T>::iterator,bool> ge_it(set<T> &s, T x) { if (s.empty()) return {s.end(), false}; auto it = s.lower_bound(x); if (it == s.end()) return {it, false}; return {it, true}; } template<class T> inline pair<typename set<T>::iterator,bool> l_it(set<T> &s, T x) { if (s.empty()) return {s.end(), false}; auto it = s.lower_bound(x); if (it == s.begin()) return {it, false}; return {prev(it), true}; } template<class T> inline pair<typename set<T>::iterator,bool> le_it(set<T> &s, T x) { if (s.empty()) return {s.end(), false}; auto it = s.upper_bound(x); if (it == s.begin()) return {it, false}; return {prev(it), true}; } template<class T> inline V<T> it_range(set<T> &st, int l, int r) { auto startIt = st.lower_bound(l); auto endIt = st.upper_bound(r); V<T> ret; for(auto itr = startIt; itr != endIt; itr++) ret.emplace_back(*itr); return ret; } template<class T> inline pair<typename multiset<T>::iterator,bool> g_it(multiset<T> &s, T x) { if (s.empty()) return {s.end(), false}; auto it = s.upper_bound(x); if (it == s.end()) return {it, false}; return {it, true}; } template<class T> inline pair<typename multiset<T>::iterator,bool> ge_it(multiset<T> &s, T x) { if (s.empty()) return {s.end(), false}; auto it = s.lower_bound(x); if (it == s.end()) return {it, false}; return {it, true}; } template<class T> inline pair<typename multiset<T>::iterator,bool> l_it(multiset<T> &s, T x) { if (s.empty()) return {s.end(), false}; auto it = s.lower_bound(x); if (it == s.begin()) return {it, false}; return {prev(it), true}; } template<class T> inline pair<typename multiset<T>::iterator,bool> le_it(multiset<T> &s, T x) { if (s.empty()) return {s.end(), false}; auto it = s.upper_bound(x); if (it == s.begin()) return {it, false}; return {prev(it), true}; } template<class T> inline V<T> it_range(multiset<T> &st, int l, int r) { auto startIt = st.lower_bound(l); auto endIt = st.upper_bound(r); V<T> ret; for(auto itr = startIt; itr != endIt; itr++) ret.emplace_back(*itr); return ret; } constexpr ll modpow(ll x,ll n,ll m=1152921504606846976LL){ll ret=1;for(;n>0;x=x*x%m,n>>=1)if(n&1)ret=ret*x%m;return ret;} constexpr ll safe_mod(ll x, ll m) {x%=m;if(x<0)x+=m;return x;} constexpr ll keta(ll n, ll base = 10LL) {ll ret = 0; while(n > 0) {n /= base, ret++;} return ret;} constexpr int pcnt(ll x) {return __builtin_popcountll(x);} constexpr int log2f(ll x) {return 63 - __builtin_clzll(x);} constexpr int log2c(ll x) {return (x==1LL)?0:(64-__builtin_clzll(x-1LL));} constexpr ll nC2(ll n) {return n*(n-1)/2;} constexpr ld deg2rad(ll degree){return (ld)degree * M_PI/180;} mt19937 rnd_engine{random_device{}()}; inline int rand(int l, int r) {uniform_int_distribution<> ret(l, r);return ret(rnd_engine);} inline ld lrand(ld l, ld r) {uniform_real_distribution<> ret(l, r);return ret(rnd_engine);} inline ld nrand(ld ave, ld var) {normal_distribution<> ret(ave, var);return ret(rnd_engine);} inline void yes(bool cond) {cout << (cond?"Yes":"No") << ENDL;} inline bool is_palindrome(const string& s){return equal(ALL(s), s.rbegin());} inline string make_palindrome(const string& s, bool odd = true) {string t = s.substr(0, SZ(s)-odd);reverse(ALL(t));return s + t;} VV<int> make_enum_vec(V<int> v){ if(v.empty()) return VV<int>(1,V<int>()); int n=v.back(); v.pop_back(); VV<int> ret,tmp=make_enum_vec(v); for(auto e:tmp)for(int i=0;i<n;++i){ret.push_back(e);ret.back().push_back(i);} return ret; } V<int> restore_path(V<int>& to, int goal, bool to1indexed = true) { V<int> ret; int x = goal; while(x >= 0) { ret.push_back(x); x = to[x]; } reverse(ALL(ret)); if (to1indexed) for(auto&& e: ret) e++; return ret; } const int dx4[4] = {1, 0, -1, 0}; const int dy4[4] = {0, 1, 0, -1}; const int dx6[6] = {1, 0, -1, 0, 1, -1}; const int dy6[6] = {0, 1, 0, -1, 1, -1}; const int dx8[8] = {1, 0, -1, 0, 1, -1, -1, 1}; const int dy8[8] = {0, 1, 0, -1, 1, 1, -1, -1}; template<class T> T extgcd(T a, T b, T& x, T& y) { for (T u = y = 1, v = x = 0; a;) { T q = b / a; swap(x -= q * u, u); swap(y -= q * v, v); swap(b -= q * a, a); } return b; } template<class T> T mod_inv(T a, T m) { T x, y; extgcd(a, m, x, y); return (m + x % m) % m; } template<int mod, int primitive_root> class NTT { public: int get_mod() const { return mod; } void _ntt(vector<ll>& a, int sign) { const int n = SZ(a); assert((n ^ (n&-n)) == 0); //n = 2^k const int g = 3; //g is primitive root of mod int h = (int)modpow(g, (mod - 1) / n, mod); // h^n = 1 if (sign == -1) h = (int)mod_inv(h, mod); //h = h^-1 % mod //bit reverse int i = 0; for (int j = 1; j < n - 1; ++j) { for (int k = n >> 1; k >(i ^= k); k >>= 1); if (j < i) swap(a[i], a[j]); } for (int m = 1; m < n; m *= 2) { const int m2 = 2 * m; const ll base = modpow(h, n / m2, mod); ll w = 1; REP(x, m) { for (int s = x; s < n; s += m2) { ll u = a[s]; ll d = a[s + m] * w % mod; a[s] = u + d; if (a[s] >= mod) a[s] -= mod; a[s + m] = u - d; if (a[s + m] < 0) a[s + m] += mod; } w = w * base % mod; } } for (auto& x : a) if (x < 0) x += mod; } void ntt(vector<ll>& input) { _ntt(input, 1); } void intt(vector<ll>& input) { _ntt(input, -1); const int n_inv = mod_inv(SZ(input), mod); for (auto& x : input) x = x * n_inv % mod; } vector<ll> convolution(const vector<ll>& a, const vector<ll>& b){ int ntt_size = 1; while (ntt_size < SZ(a) + SZ(b)) ntt_size *= 2; vector<ll> _a = a, _b = b; _a.resize(ntt_size); _b.resize(ntt_size); ntt(_a); ntt(_b); REP(i, ntt_size) (_a[i] *= _b[i]) %= mod; intt(_a); return _a; } }; using NTT_1 = NTT<167772161, 3>; using NTT_2 = NTT<469762049, 3>; using NTT_3 = NTT<1224736769, 3>; vector<ll> fast_int32mod_convolution(vector<ll> a, vector<ll> b, int mod){ for (auto& x : a) x %= mod; for (auto& x : b) x %= mod; NTT_1 ntt1; NTT_2 ntt2; NTT_3 ntt3; assert(ntt1.get_mod() < ntt2.get_mod() && ntt2.get_mod() < ntt3.get_mod()); auto x = ntt1.convolution(a, b); auto y = ntt2.convolution(a, b); auto z = ntt3.convolution(a, b); const ll m1 = ntt1.get_mod(), m2 = ntt2.get_mod(), m3 = ntt3.get_mod(); const ll m1_inv_m2 = mod_inv<ll>(m1, m2); const ll m12_inv_m3 = mod_inv<ll>(m1 * m2, m3); const ll m12_mod = m1 * m2 % mod; vector<ll> ret(SZ(x)); REP(i, SZ(x)){ ll v1 = (y[i] - x[i]) * m1_inv_m2 % m2; if (v1 < 0) v1 += m2; ll v2 = (z[i] - (x[i] + m1 * v1) % m3) * m12_inv_m3 % m3; if (v2 < 0) v2 += m3; ll constants3 = (x[i] + m1 * v1 + m12_mod * v2) % mod; if (constants3 < 0) constants3 += mod; ret[i] = constants3; } return ret; } template<class T> class Polynomial { public: std::vector<T> coef; Polynomial() : coef(1, 0) {} Polynomial(int N) : coef(N + 1, 0) {} Polynomial(std::initializer_list<T> a) : coef(a) {} Polynomial(std::string s) { using Pit = std::string::const_iterator; auto next = [&](Pit& it) { do { ++it; } while (it != s.cend() && *it == ' '); }; auto num = [&](Pit& it) -> int { int res = 0; while (it != s.cend() && std::isdigit(*it)) { res = res * 10 + (*it - '0'); next(it); } return res; }; auto atom = [&](Pit& it) -> Polynomial<T> { if (std::isdigit(*it)) { int c = num(it); return { c }; // c } else if (*it == 'x') { next(it); if (it != s.cend() && *it == '^') { next(it); int t = num(it); Polynomial<T> r(t); r[t] = 1; return r; // x^e } else { return {0, 1}; // x } } return {}; }; std::function<Polynomial<T>(Pit&)> expr; auto mono = [&](Pit& it) -> Polynomial<T> { if (*it == '(') { next(it); auto r = expr(it); next(it); if (it != s.cend() && *it == '^') { next(it); r ^= num(it); } return r; } else { return atom(it); } }; auto prod = [&](Pit& it) -> Polynomial<T> { Polynomial<T> r({ 1 }); r *= mono(it); while (it != s.cend()) { if (*it == '*') { next(it); r *= mono(it); } else if (*it == '(' || *it == 'x' || std::isdigit(*it)) { r *= mono(it); } else break; } return r; }; expr = [&](Pit& it) -> Polynomial<T> { Polynomial<T> r = prod(it); while (it != s.cend() && *it != ')') { bool neg = false; if (*it == '-') neg = true; next(it); if (neg) r -= prod(it); else r += prod(it); } return r; }; if (!s.empty() && (s.front() == '+' || s.front() == '-')) s = '0' + s; Pit it = s.cbegin(); *this = expr(it); } Polynomial(const char* s) : Polynomial(std::string(s)) {} Polynomial& operator+=(const Polynomial& r) { if (SZ(coef) < SZ(r.coef)) coef.resize(SZ(r.coef)); REP(i,SZ(r.coef)) coef[i] = safe_mod(coef[i]+r.coef[i],MOD); return *this; } Polynomial& operator-=(const Polynomial& r) { if (SZ(coef) < SZ(r.coef)) coef.resize(SZ(r.coef)); REP(i,SZ(r.coef)) coef[i] = safe_mod(coef[i]-r.coef[i],MOD); return *this; } //Polynomial& operator*=(const Polynomial & r) { // O(N^2) // std::vector<T> c(this->SZ(coef) + SZ(r.coef) - 1); // REP(i, this->SZ(coef)) REP(j, SZ(r.coef)) c[i + j] += this->coef[i] * r.coef[j]; // coef = c; // return *this; //} Polynomial& operator*=(const Polynomial& r) { // O(NlogN) this->coef = fast_int32mod_convolution(this->coef, r.coef, MOD); return *this; } Polynomial operator*(const Polynomial& r) { Polynomial res(*this); return res *= r; } Polynomial& mul_sparse(const std::map<int, T>& r, int sizeLimit = -1) { size_t sz = SZ(coef); size_t rsz = r.rbegin()->first; coef.resize(sz + rsz, 0); for (int i = sz + rsz - 1; i >= 0; --i) { for (const auto& p : r) if (p.first != 0) { if (i >= p.first) { coef[i] = safe_mod(coef[i] + safe_mod(p.second,MOD) * safe_mod(coef[i - p.first],MOD), MOD); } } } if (sizeLimit > 0 && SZ(coef) > sizeLimit) { coef.resize(sizeLimit); } return *this; } Polynomial& div_sparse(const std::map<int, T>& r, int sz = -1) { if (sz == -1) sz = SZ(coef); REP(i,sz) { for (const auto& p : r) if (p.first != 0) { if (i >= p.first) { coef[i] = safe_mod(coef[i] - safe_mod(p.second,MOD) * safe_mod(coef[i - p.first],MOD), MOD); } } } return *this; } Polynomial& operator^=(long long p) { Polynomial x(*this); *this = Polynomial(0); coef[0] = 1; while (p) { if (p & 1) (*this) *= x; x *= x; p >>= 1; } return *this; } Polynomial operator^(long long p) { Polynomial res(*this); return res ^= p; } T& operator[](size_t i) { return coef[i]; } std::vector<T> getCoef() const { return coef; } }; // get [X^N]P(X)/Q(X) in O(k logk logN) where k=deg(Q) template<class T> T coef_of_rational_polynomial(ll N, Polynomial<T> P, Polynomial<T> Q) { for (; N; N >>= 1) { Polynomial<T> Q1(Q); for (int i = 1; i < SZ(Q.coef); i += 2) Q1[i] = MOD-Q[i]; P *= Q1; int j = 0; for (int i = N & 1; i < SZ(P.coef); i += 2) P.coef[j++] = P.coef[i]; P.coef.resize(j); Q *= Q1; j = 0; for (int i = 0; i < SZ(Q.coef); i += 2) Q.coef[j++] = Q.coef[i]; Q.coef.resize(j); } return safe_mod(P[0],MOD); } #endif