hdu 2793 矩阵快速幂

a[1][1] = 0;a[1][2] = 1;a[1][3] = 0;a[1][4] = 0;
a[2][1] = 0;a[2][2] = 0;a[2][3] = 1;a[2][4] = 0;
a[3][1] = 1;a[3][2] = 1;a[3][3] = 1;a[3][4] = 0;
a[4][1] = 0;a[4][2] = 0;a[4][3] = 1;a[4][4] = 1;

#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>
using namespace std;

const __int64 MAX_N = 5;
const __int64 MOD = 1000000007;

__int64 N;

void multipy( __int64 a[MAX_N][MAX_N], __int64 b[MAX_N][MAX_N], __int64 c[MAX_N][MAX_N] ){
for( __int64 i = 1; i <= 4; i++ ){
for( __int64 j = 1; j <= 4; j++ ){
c[i][j] = 0;
for( __int64 k = 1; k <= 4; k++ ){
c[i][j] = ( c[i][j] + a[i][k] * b[k][j] % MOD ) % MOD;
}
}
}
}

void get_matrix_pow( __int64 a[MAX_N][MAX_N], __int64 n ){
__int64 ans[MAX_N][MAX_N] = {0};
__int64 temp[MAX_N][MAX_N];
for( __int64 i = 1; i <= 4; i++ )   ans[i][i] = 1;

while( n ){
if( n % 2 == 1 ){
multipy( ans, a, temp );
memcpy( ans, temp, sizeof( __int64 ) * MAX_N * MAX_N );
}
multipy( a, a, temp );
memcpy( a, temp, sizeof( __int64 ) * MAX_N * MAX_N );
n /= 2;
}
memcpy( a, ans, sizeof( __int64 ) * MAX_N * MAX_N );
}

__int64 solve( __int64 n ){
__int64 a[MAX_N][MAX_N] = {0};
if( n < 0 ){
return 0;
}
if( n == 0 ){
return 1;
}else if( n == 1 ){
return 2;
}
a[1][1] = 0;a[1][2] = 1;a[1][3] = 0;a[1][4] = 0;
a[2][1] = 0;a[2][2] = 0;a[2][3] = 1;a[2][4] = 0;
a[3][1] = 1;a[3][2] = 1;a[3][3] = 1;a[3][4] = 0;
a[4][1] = 0;a[4][2] = 0;a[4][3] = 1;a[4][4] = 1;
get_matrix_pow( a, n - 1 );
__int64 ans = 0;
__int64 b[MAX_N];
b[1] = b[2] = b[3] = 1;
b[4] = 2;
for( __int64 i = 1; i <= 4; i++ ){
ans = ( ans + a[4][i] * b[i] % MOD ) % MOD;
}
return ans;
}

int main(){
__int64 A, B;
while( scanf( "%I64d%I64d", &A, &B ) != EOF ){
printf( "%I64d\n", ( solve( B ) - solve( A - 1 ) + MOD ) % MOD );
}
return 0;
}