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FIBOSUM - Fibonacci Sum


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#include <bits/stdc++.h>
using namespace std;
#define ULL unsigned long long

ULL mod = 1000000007;

void mul(ULL a[][2] , ULL b[][2])
{
    ULL result[2][2];
    memset(result , 0 , sizeof result);
    for(int row = 0; row < 2; row++)
    {
        for(int col = 0; col < 2; col++)
        {
            for(int k = 0; k < 2; k++)
            {
                result[row][col] = (result[row][col] + (a[row][k] * b[k][col]) % mod) % mod;
            }
        }
    }

    for(int row = 0; row < 2; row++)
    {
        for(int col = 0; col < 2; col++)
        {
            a[row][col] = result[row][col];
        }
    }
}
ULL fastMatrixExpo(ULL n)
{
    ULL fib[][2] = {{0, 1}, {1, 1}};
    ULL temp[][2] = {{1, 0}, {0, 1}};

    while(n)
    {
        if(n & 1)
        {
            mul(temp, fib);
        }
        mul(fib, fib);
        n = n >> 1;
    }

    return temp[0][1];
}
int main()
{
    int t;
    ULL n, m;

    cin >> t;
    while(t--)
    {
        cin >> n >> m;
        cout<<(fastMatrixExpo(m+2) - fastMatrixExpo(n + 1) + mod)%mod<<endl;

    }
    return 0;
}

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