思路：本质与斐波那契数列一样，关键在于a与b之差

#include <iostream>
#include <vector>
using namespace std;

int main() {
  vector<long long> nums(51);
  nums[0] = 0;
  nums[1] = 1;
  nums[2] = 2;
  for (int i = 3; i < 51; i++) {
    nums[i] = nums[i - 1] + nums[i - 2];
  }
  int n, a, b;
  cin >> n;
  while (n--) {
    cin >> a >> b;
    cout << nums[b - a] << endl;
  }
  return 0;
}