#include <iostream> #include <vector> #include <algorithm> #include <numeric> #include <cassert> using namespace std; // #define DEBUG #ifdef DEBUG #define dassert(x) assert(x); #define df(...) printf(__VA_ARGS__) #else #define dassert(x) #define df(...) #endif #define x first #define y second #define mp make_pair #define pb push_back #define ir(x, a, b) ((a) <= (x) && (x) <= (b)) #define vec vector #define sz(x) (ll)x.size() #define foru(i, n) for (int i = 0; (i) < (n); ++(i)) #define all(x) (x).begin(), (x).end() typedef int64_t ll; int read() { int n = 0; bool b = 0; char c = getchar(); for (; !ir(c, '0', '9'); c = getchar()) b = (c == '-'); for (; ir(c, '0', '9'); c = getchar()) n = 10*n + (c-'0'); if (b) return -n; return n; } const ll MOD = ll(1e9)+7; ll modpow(ll a, ll b) { ll res = 1; while (b) { if (b&1) res = (res*a)%MOD; a = (a*a)%MOD, b /= 2; } return res; } int main() { df("debug mode\n"); #ifndef DEBUG ios::sync_with_stdio(0); cin.tie(0); cout.tie(0); #endif int n; cin >> n; vec<ll> a(n); vec<vec<ll>> m(n, vec<ll>(n)); foru (i, n) { cin >> a[i]; } foru (i, n) foru (j, i) { m[i][j] = m[j][i] = -gcd(a[i], a[j]); } foru (i, n) { ll s = 0; foru (j, n) { if (j == i) continue; s += m[i][j]; } m[i][i] = -s; } // foru (i, n) { // foru (j, n) { // cout << m[i][j] << " "; // } // cout << endl; // } for (auto& v : m) v.pop_back(); --n; // foru (i, n) { // foru (j, n) { // cout << m[i][j] << " "; // } // cout << endl; // } ll det = 1; for (int i = 0; i < n; ++i) { int k = -1; for (int j=i; j<n; ++j) { if (m[j][i]) { k = j; break; } } if (k == -1) { det = 0; break; } m[i].swap(m[k]); // if (i != k) // det = -det; // i dont care about the sign ll div = modpow(m[i][i], MOD-2); det = (m[i][i]*det) % MOD; for (int j=i+1; j<n; ++j) m[i][j] = (m[i][j] * div)%MOD; for (int j=0; j<n; ++j) { if (j != i && m[j][i]) for (int k=i+1; k<n; ++k) m[j][k] = (m[j][k] - ((m[i][k] * m[j][i]) % MOD) + MOD) % MOD; } } cout << abs(det) << "\n"; 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 | #include <iostream> #include <vector> #include <algorithm> #include <numeric> #include <cassert> using namespace std; // #define DEBUG #ifdef DEBUG #define dassert(x) assert(x); #define df(...) printf(__VA_ARGS__) #else #define dassert(x) #define df(...) #endif #define x first #define y second #define mp make_pair #define pb push_back #define ir(x, a, b) ((a) <= (x) && (x) <= (b)) #define vec vector #define sz(x) (ll)x.size() #define foru(i, n) for (int i = 0; (i) < (n); ++(i)) #define all(x) (x).begin(), (x).end() typedef int64_t ll; int read() { int n = 0; bool b = 0; char c = getchar(); for (; !ir(c, '0', '9'); c = getchar()) b = (c == '-'); for (; ir(c, '0', '9'); c = getchar()) n = 10*n + (c-'0'); if (b) return -n; return n; } const ll MOD = ll(1e9)+7; ll modpow(ll a, ll b) { ll res = 1; while (b) { if (b&1) res = (res*a)%MOD; a = (a*a)%MOD, b /= 2; } return res; } int main() { df("debug mode\n"); #ifndef DEBUG ios::sync_with_stdio(0); cin.tie(0); cout.tie(0); #endif int n; cin >> n; vec<ll> a(n); vec<vec<ll>> m(n, vec<ll>(n)); foru (i, n) { cin >> a[i]; } foru (i, n) foru (j, i) { m[i][j] = m[j][i] = -gcd(a[i], a[j]); } foru (i, n) { ll s = 0; foru (j, n) { if (j == i) continue; s += m[i][j]; } m[i][i] = -s; } // foru (i, n) { // foru (j, n) { // cout << m[i][j] << " "; // } // cout << endl; // } for (auto& v : m) v.pop_back(); --n; // foru (i, n) { // foru (j, n) { // cout << m[i][j] << " "; // } // cout << endl; // } ll det = 1; for (int i = 0; i < n; ++i) { int k = -1; for (int j=i; j<n; ++j) { if (m[j][i]) { k = j; break; } } if (k == -1) { det = 0; break; } m[i].swap(m[k]); // if (i != k) // det = -det; // i dont care about the sign ll div = modpow(m[i][i], MOD-2); det = (m[i][i]*det) % MOD; for (int j=i+1; j<n; ++j) m[i][j] = (m[i][j] * div)%MOD; for (int j=0; j<n; ++j) { if (j != i && m[j][i]) for (int k=i+1; k<n; ++k) m[j][k] = (m[j][k] - ((m[i][k] * m[j][i]) % MOD) + MOD) % MOD; } } cout << abs(det) << "\n"; return 0; } |