#include <cstdio> #include <iostream> #include <algorithm> #include <cstring> #include <vector> #include <set> #include <map> #include <array> #include <random> #include <cmath> #include <chrono> #include <list> #include <ctime> #include <sstream> #include <queue> #include <climits> #include <stack> #include <valarray> #include <random> #include <bitset> #include <numeric> #include <iomanip> #include <cassert> using namespace std; typedef vector<int> vi; typedef pair<int,int> pii; typedef long long ll; #define rep(x, b, e) for(int x=(b); x<(e); ++x) #define trav(a, x) for(auto& a : x) #define ford(x, b, e) for(int x=((int)(b))-1; x>=(e); --x) #define all(c) c.begin(),c.end() #define sz(x) ((int)((x).size())) #define pb push_back #define eb emplace_back #define st first #define nd second #define mp(x,y) make_pair(x,y) typedef short int sint; template<typename T> bool ckmin(T& a, const T& b){return b<a?a=b,1:0;} template<typename T> bool ckmax(T& a, const T& b){return b>a?a=b,1:0;} template <typename A, typename B> string to_string(pair<A, B> p); template <typename A, typename B, typename C> string to_string(tuple<A, B, C> p); template <typename A, typename B, typename C, typename D> string to_string(tuple<A, B, C, D> p); string to_string(const string& s) { return '"' + s + '"'; } string to_string(char c) { return string(1, c); } string to_string(const char* s) { return to_string((string) s); } string to_string(bool b) { return (b ? "true" : "false"); } string to_string(vector<bool> v) { bool first = true; string res = "{"; for (int i = 0; i < static_cast<int>(v.size()); i++) { if (!first) { res += ", "; } first = false; res += to_string(v[i]); } res += "}"; return res; } template <size_t N> string to_string(bitset<N> v) { string res = ""; for (size_t i = 0; i < N; i++) { res += static_cast<char>('0' + v[i]); } return res; } template <typename A> string to_string(A v) { bool first = true; string res = "{"; for (const auto &x : v) { if (!first) { res += ", "; } first = false; res += to_string(x); } res += "}"; return res; } template <typename A, typename B> string to_string(pair<A, B> p) { return "(" + to_string(p.first) + ", " + to_string(p.second) + ")"; } template <typename A, typename B, typename C> string to_string(tuple<A, B, C> p) { return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ")"; } template <typename A, typename B, typename C, typename D> string to_string(tuple<A, B, C, D> p) { return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ", " + to_string(get<3>(p)) + ")"; } void debug_out() { cerr << endl; } template <typename Head, typename... Tail> void debug_out(Head H, Tail... T) { cerr << " " << to_string(H); debug_out(T...); } #ifdef LOCAL #define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__) #else #define debug(...) 42 #endif template <typename T> T inverse(T a, T m) { T u = 0, v = 1; while (a != 0) { T t = m / a; m -= t * a; swap(a, m); u -= t * v; swap(u, v); } assert(m == 1); return u; } template <typename T> class Modular { public: using Type = typename decay<decltype(T::value)>::type; constexpr Modular() : value() {} template <typename U> Modular(const U& x) { value = normalize(x); } template <typename U> static Type normalize(const U& x) { Type v; if (-mod() <= x && x < mod()) v = static_cast<Type>(x); else v = static_cast<Type>(x % mod()); if (v < 0) v += mod(); return v; } const Type& operator()() const { return value; } template <typename U> explicit operator U() const { return static_cast<U>(value); } constexpr static Type mod() { return T::value; } Modular& operator+=(const Modular& other) { if ((value += other.value) >= mod()) value -= mod(); return *this; } Modular& operator-=(const Modular& other) { if ((value -= other.value) < 0) value += mod(); return *this; } template <typename U> Modular& operator+=(const U& other) { return *this += Modular(other); } template <typename U> Modular& operator-=(const U& other) { return *this -= Modular(other); } Modular& operator++() { return *this += 1; } Modular& operator--() { return *this -= 1; } Modular operator++(int) { Modular result(*this); *this += 1; return result; } Modular operator--(int) { Modular result(*this); *this -= 1; return result; } Modular operator-() const { return Modular(-value); } template <typename U = T> typename enable_if<is_same<typename Modular<U>::Type, int>::value, Modular>::type& operator*=(const Modular& rhs) { #ifdef _WIN32 uint64_t x = static_cast<int64_t>(value) * static_cast<int64_t>(rhs.value); uint32_t xh = static_cast<uint32_t>(x >> 32), xl = static_cast<uint32_t>(x), d, m; asm( "divl %4; \n\t" : "=a" (d), "=d" (m) : "d" (xh), "a" (xl), "r" (mod()) ); value = m; #else value = normalize(static_cast<int64_t>(value) * static_cast<int64_t>(rhs.value)); #endif return *this; } template <typename U = T> typename enable_if<is_same<typename Modular<U>::Type, long long>::value, Modular>::type& operator*=(const Modular& rhs) { long long q = static_cast<long long>(static_cast<long double>(value) * rhs.value / mod()); value = normalize(value * rhs.value - q * mod()); return *this; } template <typename U = T> typename enable_if<!is_integral<typename Modular<U>::Type>::value, Modular>::type& operator*=(const Modular& rhs) { value = normalize(value * rhs.value); return *this; } Modular& operator/=(const Modular& other) { return *this *= Modular(inverse(other.value, mod())); } friend const Type& abs(const Modular& x) { return x.value; } template <typename U> friend bool operator==(const Modular<U>& lhs, const Modular<U>& rhs); template <typename U> friend bool operator<(const Modular<U>& lhs, const Modular<U>& rhs); template <typename V, typename U> friend V& operator>>(V& stream, Modular<U>& number); private: Type value; }; template <typename T> bool operator==(const Modular<T>& lhs, const Modular<T>& rhs) { return lhs.value == rhs.value; } template <typename T, typename U> bool operator==(const Modular<T>& lhs, U rhs) { return lhs == Modular<T>(rhs); } template <typename T, typename U> bool operator==(U lhs, const Modular<T>& rhs) { return Modular<T>(lhs) == rhs; } template <typename T> bool operator!=(const Modular<T>& lhs, const Modular<T>& rhs) { return !(lhs == rhs); } template <typename T, typename U> bool operator!=(const Modular<T>& lhs, U rhs) { return !(lhs == rhs); } template <typename T, typename U> bool operator!=(U lhs, const Modular<T>& rhs) { return !(lhs == rhs); } template <typename T> bool operator<(const Modular<T>& lhs, const Modular<T>& rhs) { return lhs.value < rhs.value; } template <typename T> Modular<T> operator+(const Modular<T>& lhs, const Modular<T>& rhs) { return Modular<T>(lhs) += rhs; } template <typename T, typename U> Modular<T> operator+(const Modular<T>& lhs, U rhs) { return Modular<T>(lhs) += rhs; } template <typename T, typename U> Modular<T> operator+(U lhs, const Modular<T>& rhs) { return Modular<T>(lhs) += rhs; } template <typename T> Modular<T> operator-(const Modular<T>& lhs, const Modular<T>& rhs) { return Modular<T>(lhs) -= rhs; } template <typename T, typename U> Modular<T> operator-(const Modular<T>& lhs, U rhs) { return Modular<T>(lhs) -= rhs; } template <typename T, typename U> Modular<T> operator-(U lhs, const Modular<T>& rhs) { return Modular<T>(lhs) -= rhs; } template <typename T> Modular<T> operator*(const Modular<T>& lhs, const Modular<T>& rhs) { return Modular<T>(lhs) *= rhs; } template <typename T, typename U> Modular<T> operator*(const Modular<T>& lhs, U rhs) { return Modular<T>(lhs) *= rhs; } template <typename T, typename U> Modular<T> operator*(U lhs, const Modular<T>& rhs) { return Modular<T>(lhs) *= rhs; } template <typename T> Modular<T> operator/(const Modular<T>& lhs, const Modular<T>& rhs) { return Modular<T>(lhs) /= rhs; } template <typename T, typename U> Modular<T> operator/(const Modular<T>& lhs, U rhs) { return Modular<T>(lhs) /= rhs; } template <typename T, typename U> Modular<T> operator/(U lhs, const Modular<T>& rhs) { return Modular<T>(lhs) /= rhs; } template<typename T, typename U> Modular<T> power(const Modular<T>& a, const U& b) { assert(b >= 0); Modular<T> x = a, res = 1; U p = b; while (p > 0) { if (p & 1) res *= x; x *= x; p >>= 1; } return res; } template <typename T> bool IsZero(const Modular<T>& number) { return number() == 0; } template <typename T> string to_string(const Modular<T>& number) { return to_string(number()); } // U == std::ostream? but done this way because of fastoutput template <typename U, typename T> U& operator<<(U& stream, const Modular<T>& number) { return stream << number(); } // U == std::istream? but done this way because of fastinput template <typename U, typename T> U& operator>>(U& stream, Modular<T>& number) { typename common_type<typename Modular<T>::Type, long long>::type x; stream >> x; number.value = Modular<T>::normalize(x); return stream; } /* using ModType = int; struct VarMod { static ModType value; }; ModType VarMod::value; ModType& md = VarMod::value; using Mint = Modular<VarMod>; */ constexpr int md = (int) 1e9 + 7; using Mint = Modular<std::integral_constant<decay<decltype(md)>::type, md>>; /*vector<Mint> fact; vector<Mint> inv_fact; Mint C(int n, int k) { if (k < 0 || k > n) { return 0; } if (fact.empty()) { fact = {1, 1}; inv_fact = {1, 1}; } while ((int) fact.size() < n + 1) { fact.push_back(fact.back() * (int) fact.size()); inv_fact.push_back(1 / fact.back()); } return fact[n] * inv_fact[k] * inv_fact[n - k]; }*/ mt19937 rng(chrono::steady_clock::now().time_since_epoch().count()); // use rng() to get unsigned int // mt19937_64 for random long longs const int N = 20; int a[N]; int n, m; int res = 0, nres; bool check(const vi& b) { // checkuje b vector<vi> f(sz(b) + 1, vi(sz(b) + 1)); // rep(i, 0, n) { // printf("%d ", a[i]); // } // printf("\n"); rep(diff, 1, sz(b)) { rep(j, 1, sz(b) + 1) { int k = j + diff; if (k > sz(b)) break; // f[j][k] if (b[j - 1] == b[k- 1]) { f[j][k] = 1; } else { rep(l, j + 1, k) { if (b[l - 1] == b[j - 1]) { f[j][k] |= f[l + 1][k]; } } } } } if (f[1][sz(b)]) { // if (a[0] != 1) return true; ++res; // rep(i, 0, n) { // cout << a[i] << ' '; // } // cout << endl; return true; } return false; } bool check2(const vi& b) { if (b[0] == 2) return false; auto b2 = b; b2.pb(2); if (check(b2)) return false; rep(i, 0, sz(b) - 1) { if (b[i] == 1) { // debug(i, sz(b)); auto b2 = vi(b.begin() + i + 1, b.end()); b2.pb(2); if (check(b2)) return false; } } ++nres; rep(i, 0, n) { cout << b[i] << ' '; } cout << endl; return true; } void gener(int idx) { if (idx == n) { vi pom(n); rep(i, 0, n) pom[i] = a[i]; check(pom); // check2(pom); return; } rep(i, 1, m + 1) { a[idx] = i; gener(idx + 1); } } void solve() { cin >> n >> m; res = 0, nres = 0; if (n == 1) { cout << 0 << endl; } else if (m == 1) { cout << 1 << endl; } else { a[0] = 1; gener(1); cout << (Mint(res) * m)() << endl; } } // void solve() { // int gr = 10; // int M = 4; // for (m = 2; m <= M; ++m) { // for (n = 2; n <= gr; ++n) { // res = nres = 0; // gener(0); // debug(n, m, res); // } // } // } int main() { ios_base::sync_with_stdio(false); cin.tie(0); int t; // cin >> t; t = 1; while (t--) { solve(); } }
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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 | #include <cstdio> #include <iostream> #include <algorithm> #include <cstring> #include <vector> #include <set> #include <map> #include <array> #include <random> #include <cmath> #include <chrono> #include <list> #include <ctime> #include <sstream> #include <queue> #include <climits> #include <stack> #include <valarray> #include <random> #include <bitset> #include <numeric> #include <iomanip> #include <cassert> using namespace std; typedef vector<int> vi; typedef pair<int,int> pii; typedef long long ll; #define rep(x, b, e) for(int x=(b); x<(e); ++x) #define trav(a, x) for(auto& a : x) #define ford(x, b, e) for(int x=((int)(b))-1; x>=(e); --x) #define all(c) c.begin(),c.end() #define sz(x) ((int)((x).size())) #define pb push_back #define eb emplace_back #define st first #define nd second #define mp(x,y) make_pair(x,y) typedef short int sint; template<typename T> bool ckmin(T& a, const T& b){return b<a?a=b,1:0;} template<typename T> bool ckmax(T& a, const T& b){return b>a?a=b,1:0;} template <typename A, typename B> string to_string(pair<A, B> p); template <typename A, typename B, typename C> string to_string(tuple<A, B, C> p); template <typename A, typename B, typename C, typename D> string to_string(tuple<A, B, C, D> p); string to_string(const string& s) { return '"' + s + '"'; } string to_string(char c) { return string(1, c); } string to_string(const char* s) { return to_string((string) s); } string to_string(bool b) { return (b ? "true" : "false"); } string to_string(vector<bool> v) { bool first = true; string res = "{"; for (int i = 0; i < static_cast<int>(v.size()); i++) { if (!first) { res += ", "; } first = false; res += to_string(v[i]); } res += "}"; return res; } template <size_t N> string to_string(bitset<N> v) { string res = ""; for (size_t i = 0; i < N; i++) { res += static_cast<char>('0' + v[i]); } return res; } template <typename A> string to_string(A v) { bool first = true; string res = "{"; for (const auto &x : v) { if (!first) { res += ", "; } first = false; res += to_string(x); } res += "}"; return res; } template <typename A, typename B> string to_string(pair<A, B> p) { return "(" + to_string(p.first) + ", " + to_string(p.second) + ")"; } template <typename A, typename B, typename C> string to_string(tuple<A, B, C> p) { return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ")"; } template <typename A, typename B, typename C, typename D> string to_string(tuple<A, B, C, D> p) { return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ", " + to_string(get<3>(p)) + ")"; } void debug_out() { cerr << endl; } template <typename Head, typename... Tail> void debug_out(Head H, Tail... T) { cerr << " " << to_string(H); debug_out(T...); } #ifdef LOCAL #define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__) #else #define debug(...) 42 #endif template <typename T> T inverse(T a, T m) { T u = 0, v = 1; while (a != 0) { T t = m / a; m -= t * a; swap(a, m); u -= t * v; swap(u, v); } assert(m == 1); return u; } template <typename T> class Modular { public: using Type = typename decay<decltype(T::value)>::type; constexpr Modular() : value() {} template <typename U> Modular(const U& x) { value = normalize(x); } template <typename U> static Type normalize(const U& x) { Type v; if (-mod() <= x && x < mod()) v = static_cast<Type>(x); else v = static_cast<Type>(x % mod()); if (v < 0) v += mod(); return v; } const Type& operator()() const { return value; } template <typename U> explicit operator U() const { return static_cast<U>(value); } constexpr static Type mod() { return T::value; } Modular& operator+=(const Modular& other) { if ((value += other.value) >= mod()) value -= mod(); return *this; } Modular& operator-=(const Modular& other) { if ((value -= other.value) < 0) value += mod(); return *this; } template <typename U> Modular& operator+=(const U& other) { return *this += Modular(other); } template <typename U> Modular& operator-=(const U& other) { return *this -= Modular(other); } Modular& operator++() { return *this += 1; } Modular& operator--() { return *this -= 1; } Modular operator++(int) { Modular result(*this); *this += 1; return result; } Modular operator--(int) { Modular result(*this); *this -= 1; return result; } Modular operator-() const { return Modular(-value); } template <typename U = T> typename enable_if<is_same<typename Modular<U>::Type, int>::value, Modular>::type& operator*=(const Modular& rhs) { #ifdef _WIN32 uint64_t x = static_cast<int64_t>(value) * static_cast<int64_t>(rhs.value); uint32_t xh = static_cast<uint32_t>(x >> 32), xl = static_cast<uint32_t>(x), d, m; asm( "divl %4; \n\t" : "=a" (d), "=d" (m) : "d" (xh), "a" (xl), "r" (mod()) ); value = m; #else value = normalize(static_cast<int64_t>(value) * static_cast<int64_t>(rhs.value)); #endif return *this; } template <typename U = T> typename enable_if<is_same<typename Modular<U>::Type, long long>::value, Modular>::type& operator*=(const Modular& rhs) { long long q = static_cast<long long>(static_cast<long double>(value) * rhs.value / mod()); value = normalize(value * rhs.value - q * mod()); return *this; } template <typename U = T> typename enable_if<!is_integral<typename Modular<U>::Type>::value, Modular>::type& operator*=(const Modular& rhs) { value = normalize(value * rhs.value); return *this; } Modular& operator/=(const Modular& other) { return *this *= Modular(inverse(other.value, mod())); } friend const Type& abs(const Modular& x) { return x.value; } template <typename U> friend bool operator==(const Modular<U>& lhs, const Modular<U>& rhs); template <typename U> friend bool operator<(const Modular<U>& lhs, const Modular<U>& rhs); template <typename V, typename U> friend V& operator>>(V& stream, Modular<U>& number); private: Type value; }; template <typename T> bool operator==(const Modular<T>& lhs, const Modular<T>& rhs) { return lhs.value == rhs.value; } template <typename T, typename U> bool operator==(const Modular<T>& lhs, U rhs) { return lhs == Modular<T>(rhs); } template <typename T, typename U> bool operator==(U lhs, const Modular<T>& rhs) { return Modular<T>(lhs) == rhs; } template <typename T> bool operator!=(const Modular<T>& lhs, const Modular<T>& rhs) { return !(lhs == rhs); } template <typename T, typename U> bool operator!=(const Modular<T>& lhs, U rhs) { return !(lhs == rhs); } template <typename T, typename U> bool operator!=(U lhs, const Modular<T>& rhs) { return !(lhs == rhs); } template <typename T> bool operator<(const Modular<T>& lhs, const Modular<T>& rhs) { return lhs.value < rhs.value; } template <typename T> Modular<T> operator+(const Modular<T>& lhs, const Modular<T>& rhs) { return Modular<T>(lhs) += rhs; } template <typename T, typename U> Modular<T> operator+(const Modular<T>& lhs, U rhs) { return Modular<T>(lhs) += rhs; } template <typename T, typename U> Modular<T> operator+(U lhs, const Modular<T>& rhs) { return Modular<T>(lhs) += rhs; } template <typename T> Modular<T> operator-(const Modular<T>& lhs, const Modular<T>& rhs) { return Modular<T>(lhs) -= rhs; } template <typename T, typename U> Modular<T> operator-(const Modular<T>& lhs, U rhs) { return Modular<T>(lhs) -= rhs; } template <typename T, typename U> Modular<T> operator-(U lhs, const Modular<T>& rhs) { return Modular<T>(lhs) -= rhs; } template <typename T> Modular<T> operator*(const Modular<T>& lhs, const Modular<T>& rhs) { return Modular<T>(lhs) *= rhs; } template <typename T, typename U> Modular<T> operator*(const Modular<T>& lhs, U rhs) { return Modular<T>(lhs) *= rhs; } template <typename T, typename U> Modular<T> operator*(U lhs, const Modular<T>& rhs) { return Modular<T>(lhs) *= rhs; } template <typename T> Modular<T> operator/(const Modular<T>& lhs, const Modular<T>& rhs) { return Modular<T>(lhs) /= rhs; } template <typename T, typename U> Modular<T> operator/(const Modular<T>& lhs, U rhs) { return Modular<T>(lhs) /= rhs; } template <typename T, typename U> Modular<T> operator/(U lhs, const Modular<T>& rhs) { return Modular<T>(lhs) /= rhs; } template<typename T, typename U> Modular<T> power(const Modular<T>& a, const U& b) { assert(b >= 0); Modular<T> x = a, res = 1; U p = b; while (p > 0) { if (p & 1) res *= x; x *= x; p >>= 1; } return res; } template <typename T> bool IsZero(const Modular<T>& number) { return number() == 0; } template <typename T> string to_string(const Modular<T>& number) { return to_string(number()); } // U == std::ostream? but done this way because of fastoutput template <typename U, typename T> U& operator<<(U& stream, const Modular<T>& number) { return stream << number(); } // U == std::istream? but done this way because of fastinput template <typename U, typename T> U& operator>>(U& stream, Modular<T>& number) { typename common_type<typename Modular<T>::Type, long long>::type x; stream >> x; number.value = Modular<T>::normalize(x); return stream; } /* using ModType = int; struct VarMod { static ModType value; }; ModType VarMod::value; ModType& md = VarMod::value; using Mint = Modular<VarMod>; */ constexpr int md = (int) 1e9 + 7; using Mint = Modular<std::integral_constant<decay<decltype(md)>::type, md>>; /*vector<Mint> fact; vector<Mint> inv_fact; Mint C(int n, int k) { if (k < 0 || k > n) { return 0; } if (fact.empty()) { fact = {1, 1}; inv_fact = {1, 1}; } while ((int) fact.size() < n + 1) { fact.push_back(fact.back() * (int) fact.size()); inv_fact.push_back(1 / fact.back()); } return fact[n] * inv_fact[k] * inv_fact[n - k]; }*/ mt19937 rng(chrono::steady_clock::now().time_since_epoch().count()); // use rng() to get unsigned int // mt19937_64 for random long longs const int N = 20; int a[N]; int n, m; int res = 0, nres; bool check(const vi& b) { // checkuje b vector<vi> f(sz(b) + 1, vi(sz(b) + 1)); // rep(i, 0, n) { // printf("%d ", a[i]); // } // printf("\n"); rep(diff, 1, sz(b)) { rep(j, 1, sz(b) + 1) { int k = j + diff; if (k > sz(b)) break; // f[j][k] if (b[j - 1] == b[k- 1]) { f[j][k] = 1; } else { rep(l, j + 1, k) { if (b[l - 1] == b[j - 1]) { f[j][k] |= f[l + 1][k]; } } } } } if (f[1][sz(b)]) { // if (a[0] != 1) return true; ++res; // rep(i, 0, n) { // cout << a[i] << ' '; // } // cout << endl; return true; } return false; } bool check2(const vi& b) { if (b[0] == 2) return false; auto b2 = b; b2.pb(2); if (check(b2)) return false; rep(i, 0, sz(b) - 1) { if (b[i] == 1) { // debug(i, sz(b)); auto b2 = vi(b.begin() + i + 1, b.end()); b2.pb(2); if (check(b2)) return false; } } ++nres; rep(i, 0, n) { cout << b[i] << ' '; } cout << endl; return true; } void gener(int idx) { if (idx == n) { vi pom(n); rep(i, 0, n) pom[i] = a[i]; check(pom); // check2(pom); return; } rep(i, 1, m + 1) { a[idx] = i; gener(idx + 1); } } void solve() { cin >> n >> m; res = 0, nres = 0; if (n == 1) { cout << 0 << endl; } else if (m == 1) { cout << 1 << endl; } else { a[0] = 1; gener(1); cout << (Mint(res) * m)() << endl; } } // void solve() { // int gr = 10; // int M = 4; // for (m = 2; m <= M; ++m) { // for (n = 2; n <= gr; ++n) { // res = nres = 0; // gener(0); // debug(n, m, res); // } // } // } int main() { ios_base::sync_with_stdio(false); cin.tie(0); int t; // cin >> t; t = 1; while (t--) { solve(); } } |