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  1. #include <bits/stdc++.h>
  2. #define FNAME "CANDY"
  3. using namespace std;
  4. const int MAXN = 501;
  5. typedef long long ll;
  6. const int MOD = 1e9 + 7;
  7.  
  8. void fastip() {
  9.     ios_base::sync_with_stdio(0);
  10.     cin.tie(0); cout.tie(0);
  11.     if (fopen(FNAME".inp", "r")) {
  12.         freopen(FNAME".inp", "r", stdin);
  13.         freopen(FNAME".out", "w", stdout);
  14.     }
  15. }
  16.  
  17. long long n;
  18.  
  19. struct Matrix{
  20.     int n , m;
  21.     vector<vector<long long>> f;
  22.  
  23.     Matrix(int N, int M){
  24.         n = N;
  25.         m = M;
  26.         if(N > 0 && M > 0){
  27.             f.resize(n, vector<long long>(m , 0));
  28.         }
  29.     }
  30.  
  31.     void Unit(){
  32.         for(int i = 0; i < n ; i++){
  33.             f[i][i] = 1;
  34.         }
  35.     }
  36.  
  37.     Matrix operator * (const Matrix &other) const {
  38.         Matrix res(n , other.m);
  39.         for(int i = 0; i < n ; i++){
  40.             for(int j = 0; j < other.m ; j++){
  41.                 long long total = 0;
  42.                 for(int k = 0; k < m ; k++){
  43.                     total = (total + f[i][k] * other.f[k][j]) % MOD;
  44.                 }
  45.                 res.f[i][j] = total % MOD;
  46.             }
  47.         }
  48.         return res;
  49.     }
  50. };
  51.  
  52. Matrix to_Unit(2, 2);
  53.  
  54. Matrix Pow(Matrix t, long long index){
  55.     if(!index) return to_Unit;
  56.     Matrix tmp = Pow(t, index / 2);
  57.     if(index % 2 == 0){
  58.         return tmp * tmp;
  59.     }
  60.     return tmp * tmp * t;
  61. }
  62.  
  63. int main(){
  64.     fastip();
  65.     to_Unit.Unit();
  66.  
  67.     cin >> n;
  68.  
  69.     Matrix T(2 , 2);
  70.  
  71.     T.f = {
  72.         {1 , 1},
  73.         {1 , 0}
  74.     };
  75.  
  76.     Matrix dp(2, 1);
  77.  
  78.     dp.f = {
  79.         {1},
  80.         {0}
  81.     };
  82.  
  83.     Matrix res = Pow(T, n - 1);
  84.     res = res * dp;
  85.  
  86.     if(n == 0) cout << 0;
  87.     else cout << res.f[0][0];
  88.  
  89.     return 0;
  90. }
Success #stdin #stdout 0.01s 5288KB
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https://ideone.com/ouhmsi
language:
C++ (gcc 8.3)
created:
6 days ago
visibility:
public

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