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fib_matrix.cpp
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//
// fib_matrix.cpp
//
#include "fib_matrix.hpp"
void matrix_mult(int M1[2][2], int M2[2][2]) {
int x00 = M1[0][0]*M2[0][0] + M1[0][1]*M2[1][0];
int x01 = M1[0][0]*M2[0][1] + M1[0][1]*M2[1][1];
int x10 = M1[1][0]*M2[0][0] + M1[1][1]*M2[1][0];
int x11 = M1[1][0]*M2[0][1] + M1[1][1]*M2[1][1];
M1[0][0] = x00;
M1[0][1] = x01;
M1[1][0] = x10;
M1[1][1] = x11;
}
void matrix_mult_mod(unsigned int M1[2][2], unsigned int M2[2][2]) {
unsigned int x00 = ((M1[0][0] * M2[0][0]) + (M1[0][1] * M2[1][0])) % MODULO;
unsigned int x01 = ((M1[0][0] * M2[0][1]) + (M1[0][1] * M2[1][1])) % MODULO;
unsigned int x10 = ((M1[1][0] * M2[0][0]) + (M1[1][1] * M2[1][0])) % MODULO;
unsigned int x11 = ((M1[1][0] * M2[0][1]) + (M1[1][1] * M2[1][1])) % MODULO;
M1[0][0] = x00;
M1[0][1] = x01;
M1[1][0] = x10;
M1[1][1] = x11;
}
void matrix_power(int M[2][2], int n) {
if (n == 0 || n == 1) return;
int N[2][2] = {{1, 1}, {1, 0}};
matrix_power(M, n/2);
matrix_mult(M, M);
if (n % 2 != 0) matrix_mult(M, N);
}
void matrix_power_mod(unsigned int M[2][2], unsigned int n) {
if (n == 0 || n == 1) return;
unsigned int N[2][2] = {{1, 1}, {1, 0}};
matrix_power_mod(M, n/2);
matrix_mult_mod(M, M);
if (n % 2 != 0) matrix_mult_mod(M, N);
}
int fib_matrix(int n) {
if (n == 0 || n == 1) return n;
int M[2][2] = {{1, 1}, {1, 0}};
matrix_power(M, n-1);
return M[0][0];
}
int fib_matrix_mod(unsigned int n) {
if (n == 0 || n == 1) return n;
unsigned int M[2][2] = {{1, 1}, {1, 0}};
matrix_power_mod(M, n-1);
return M[0][0];
}