#include <bits/stdc++.h> #define dbg(x) " [" << #x << ": " << (x) << "] " using namespace std; template<typename A, typename B> ostream& operator<<(ostream& out, const pair<A,B>& p) { return out << "(" << p.first << ", " << p.second << ")"; } template<typename T> ostream& operator<<(ostream& out, const vector<T>& c) { out << "{"; for(auto it = c.begin(); it != c.end(); it++) { if(it != c.begin()) out << ", "; out << *it; } return out << "}" << endl; } const int mod = 1e9 + 7; vector<vector<long long>> v; long long bp(long long a, long long b) { long long res = 1; while(b) { if(b & 1) res = res * a % mod; a = a * a % mod; b >>= 1; } return res; } int comp() { int n = v.size(); long long det = 1; for(int i = 0; i < n; i++) { int p = i; for(int j = i + 1; j < n; j++) { if(v[j][i]) { p = j; break; } } if(!v[p][i]) { return 0; } if(i != p) { swap(v[i], v[p]); if(det) det = mod - det; } det = det * v[i][i] % mod; long long inv = bp(v[i][i], mod - 2); for(int j = i + 1; j < n; j++) { v[i][j] = v[i][j] * inv % mod; } for(int j = i + 1; j < n; j++) { if(v[j][i]) { for(int k = i + 1; k < n; k++) { v[j][k] = (v[j][k] + mod - (v[j][i] * v[i][k] % mod)) % mod; } } } } return det; } int main() { ios_base::sync_with_stdio(false); cin.tie(0); int n; cin >> n; vector<int> vv(n); for(int& i : vv) cin >> i; if(n == 1) { cout << 1 << endl; return 0; } v.assign(n - 1, vector<long long>(n - 1)); for(int i = 0; i < n - 1; i++) { int s = 0; for(int j = 0; j < n; j++) { if(i != j) { int x = -gcd(vv[i], vv[j]); s -= x; if(j < n - 1) v[i][j] = mod + x; } } v[i][i] = s; } cout << comp() << endl; 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 | #include <bits/stdc++.h> #define dbg(x) " [" << #x << ": " << (x) << "] " using namespace std; template<typename A, typename B> ostream& operator<<(ostream& out, const pair<A,B>& p) { return out << "(" << p.first << ", " << p.second << ")"; } template<typename T> ostream& operator<<(ostream& out, const vector<T>& c) { out << "{"; for(auto it = c.begin(); it != c.end(); it++) { if(it != c.begin()) out << ", "; out << *it; } return out << "}" << endl; } const int mod = 1e9 + 7; vector<vector<long long>> v; long long bp(long long a, long long b) { long long res = 1; while(b) { if(b & 1) res = res * a % mod; a = a * a % mod; b >>= 1; } return res; } int comp() { int n = v.size(); long long det = 1; for(int i = 0; i < n; i++) { int p = i; for(int j = i + 1; j < n; j++) { if(v[j][i]) { p = j; break; } } if(!v[p][i]) { return 0; } if(i != p) { swap(v[i], v[p]); if(det) det = mod - det; } det = det * v[i][i] % mod; long long inv = bp(v[i][i], mod - 2); for(int j = i + 1; j < n; j++) { v[i][j] = v[i][j] * inv % mod; } for(int j = i + 1; j < n; j++) { if(v[j][i]) { for(int k = i + 1; k < n; k++) { v[j][k] = (v[j][k] + mod - (v[j][i] * v[i][k] % mod)) % mod; } } } } return det; } int main() { ios_base::sync_with_stdio(false); cin.tie(0); int n; cin >> n; vector<int> vv(n); for(int& i : vv) cin >> i; if(n == 1) { cout << 1 << endl; return 0; } v.assign(n - 1, vector<long long>(n - 1)); for(int i = 0; i < n - 1; i++) { int s = 0; for(int j = 0; j < n; j++) { if(i != j) { int x = -gcd(vv[i], vv[j]); s -= x; if(j < n - 1) v[i][j] = mod + x; } } v[i][i] = s; } cout << comp() << endl; return 0; } |