// Krzysztof Małysa #include <bits/stdc++.h> using namespace std; #define FOR(i,a,n) for (auto i = (a), i ## __ = (n); i <= i ## __; ++i) #define FORD(i,a,n) for (auto i = (a), i ## __ = (n); i >= i ## __; --i) #define REP(i,n) FOR(i, 0, n - 1) #define ALL(x) x.begin(), x.end() #define SZ(x) (int(x.size())) #define EB emplace_back #define ST first #define ND second #define tpv typedef vector< typedef long long LL; typedef pair<int, int> PII; tpv int> VI; tpv VI> VVI; tpv PII> VPII; tpv LL> VLL; constexpr char nl = '\n'; #define endl nl #define ris return *this #define tem template<class T tem, class B> inline void mini(T&& a, B&& b) { if (b < a) a = b; } tem, class B> inline void maxi(T&& a, B&& b) { if (b > a) a = b; } int ceil2(int x) { return x < 2 ? 1 : 1 << (sizeof(x) * 8 - __builtin_clz(x - 1)); } tem> struct Dump { T a, b; }; tem> auto dump(T&& x) -> Dump<decltype(x.begin())> { return {ALL(x)}; } struct Debug { ~Debug() { cerr << endl; } tem> auto operator<<(T x) -> decltype(cerr << x, *this) { cerr << boolalpha << x; return *this; } tem> auto operator<<(T x) -> decltype(x.begin(), *this) { auto a = x.begin(), b = x.end(); *this << "{"; for (; a != b;) *this << *a++, *this << (a == b ? "" : " "); return *this << "}"; } tem, class B> Debug& operator<<(pair<T, B> p) { ris << "(" << p.ST << ", " << p.ND << ")"; } tem> Debug& operator<<(Dump<T> d) { *this << "{\n"; for (T a = d.a, c = a; a != d.b; ++a) *this << " " << distance(c, a) << ": " << *a << '\n'; ris << "}"; } }; struct Foo {tem>Foo& operator<<(T) {ris;}}; #ifdef DEBUG # define deb Debug() #else # define deb Foo() #endif #define imie(x...) #x ": " << (x) << " " #define LOG(x...) deb << imie(x) #define DOG(x...) deb << #x ": " << dump(x) << " " template<class I> void inplace_sort(I a, I b) { make_heap(a, b); sort_heap(a, b); } LL n; void span(VLL& S, VI primes) { // This way to preserve reserve() xd S.resize(1); S[0] = 1; // Fill S for (int p : primes) { int sz = SZ(S); for (LL a = p; a < n; a *= p) { REP (i, sz) { if (S[i] > n / a) break; S.EB(S[i] * a); } // Prevents long long overflow if (a > n / p) break; } // sort(ALL(S)); inplace_sort(ALL(S)); } } int main() { ios::sync_with_stdio(false); cin.tie(nullptr); int k; cin >> k >> n; VLL S1, S2, S3; S1 = S2 = S3 = {1}; VI primes(k); for (int& x : primes) cin >> x; sort(ALL(primes)); auto extract_l_elems = [&](int l) { mini(l, SZ(primes)); VI res(primes.begin(), primes.begin() + l); primes.erase(primes.begin(), primes.begin() + l); return res; }; // First 5 elements S1.reserve(276997); VI p1 = extract_l_elems(5); span(S1, p1); // Next 8 elements S2.reserve(167288); VI p2 = extract_l_elems(8); span(S2, p2); // Last 12 elements S3.reserve(396247); VI p3 = extract_l_elems(12); span(S3, p3); LOG(p1); LOG(p2); LOG(p3); LOG(SZ(S1)); LOG(SZ(S2)); LOG(SZ(S3)); LL res = 1; // Meet in the middle S2 and S3 and binsearch in S1 for (LL x : S2) { LL boundary = n / x; for (LL y : S3) { if (y > boundary) break; LL e = x * y; // Element maxi(res, e); maxi(res, e * *--upper_bound(ALL(S1), n / e)); } } cout << res << nl; return 0; }
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 | // Krzysztof Małysa #include <bits/stdc++.h> using namespace std; #define FOR(i,a,n) for (auto i = (a), i ## __ = (n); i <= i ## __; ++i) #define FORD(i,a,n) for (auto i = (a), i ## __ = (n); i >= i ## __; --i) #define REP(i,n) FOR(i, 0, n - 1) #define ALL(x) x.begin(), x.end() #define SZ(x) (int(x.size())) #define EB emplace_back #define ST first #define ND second #define tpv typedef vector< typedef long long LL; typedef pair<int, int> PII; tpv int> VI; tpv VI> VVI; tpv PII> VPII; tpv LL> VLL; constexpr char nl = '\n'; #define endl nl #define ris return *this #define tem template<class T tem, class B> inline void mini(T&& a, B&& b) { if (b < a) a = b; } tem, class B> inline void maxi(T&& a, B&& b) { if (b > a) a = b; } int ceil2(int x) { return x < 2 ? 1 : 1 << (sizeof(x) * 8 - __builtin_clz(x - 1)); } tem> struct Dump { T a, b; }; tem> auto dump(T&& x) -> Dump<decltype(x.begin())> { return {ALL(x)}; } struct Debug { ~Debug() { cerr << endl; } tem> auto operator<<(T x) -> decltype(cerr << x, *this) { cerr << boolalpha << x; return *this; } tem> auto operator<<(T x) -> decltype(x.begin(), *this) { auto a = x.begin(), b = x.end(); *this << "{"; for (; a != b;) *this << *a++, *this << (a == b ? "" : " "); return *this << "}"; } tem, class B> Debug& operator<<(pair<T, B> p) { ris << "(" << p.ST << ", " << p.ND << ")"; } tem> Debug& operator<<(Dump<T> d) { *this << "{\n"; for (T a = d.a, c = a; a != d.b; ++a) *this << " " << distance(c, a) << ": " << *a << '\n'; ris << "}"; } }; struct Foo {tem>Foo& operator<<(T) {ris;}}; #ifdef DEBUG # define deb Debug() #else # define deb Foo() #endif #define imie(x...) #x ": " << (x) << " " #define LOG(x...) deb << imie(x) #define DOG(x...) deb << #x ": " << dump(x) << " " template<class I> void inplace_sort(I a, I b) { make_heap(a, b); sort_heap(a, b); } LL n; void span(VLL& S, VI primes) { // This way to preserve reserve() xd S.resize(1); S[0] = 1; // Fill S for (int p : primes) { int sz = SZ(S); for (LL a = p; a < n; a *= p) { REP (i, sz) { if (S[i] > n / a) break; S.EB(S[i] * a); } // Prevents long long overflow if (a > n / p) break; } // sort(ALL(S)); inplace_sort(ALL(S)); } } int main() { ios::sync_with_stdio(false); cin.tie(nullptr); int k; cin >> k >> n; VLL S1, S2, S3; S1 = S2 = S3 = {1}; VI primes(k); for (int& x : primes) cin >> x; sort(ALL(primes)); auto extract_l_elems = [&](int l) { mini(l, SZ(primes)); VI res(primes.begin(), primes.begin() + l); primes.erase(primes.begin(), primes.begin() + l); return res; }; // First 5 elements S1.reserve(276997); VI p1 = extract_l_elems(5); span(S1, p1); // Next 8 elements S2.reserve(167288); VI p2 = extract_l_elems(8); span(S2, p2); // Last 12 elements S3.reserve(396247); VI p3 = extract_l_elems(12); span(S3, p3); LOG(p1); LOG(p2); LOG(p3); LOG(SZ(S1)); LOG(SZ(S2)); LOG(SZ(S3)); LL res = 1; // Meet in the middle S2 and S3 and binsearch in S1 for (LL x : S2) { LL boundary = n / x; for (LL y : S3) { if (y > boundary) break; LL e = x * y; // Element maxi(res, e); maxi(res, e * *--upper_bound(ALL(S1), n / e)); } } cout << res << nl; return 0; } |