@param n `0 <= n` @param m `1 <= m` @return `(x ** n) % m`
| 64 | // @param m `1 <= m` |
| 65 | // @return `(x ** n) % m` |
| 66 | constexpr long long pow_mod_constexpr(long long x, long long n, int m) { |
| 67 | if (m == 1) return 0; |
| 68 | unsigned int _m = (unsigned int)(m); |
| 69 | unsigned long long r = 1; |
| 70 | unsigned long long y = safe_mod(x, m); |
| 71 | while (n) { |
| 72 | if (n & 1) r = (r * y) % _m; |
| 73 | y = (y * y) % _m; |
| 74 | n >>= 1; |
| 75 | } |
| 76 | return r; |
| 77 | } |
| 78 | |
| 79 | // Reference: |
| 80 | // M. Forisek and J. Jancina, |