use std::convert::TryInto;

pub fn two_sum(numbers: Vec<i32>, target: i32) -> Vec<i32> {
  for (index_1, number_1) in numbers.iter().enumerate() {
    for (index_2, number_2) in numbers.iter().enumerate() {
      if index_1 == index_2 {
        continue;
      }

      if number_1 + number_2 == target {
        return vec![index_1.try_into().unwrap(), index_2.try_into().unwrap()];
      }
    }
  }

  panic!("No pair of numbers found that sum to {}", target)
}

#[test]
fn test_two_sum() {
  assert_eq!(two_sum(vec![2, 7, 11, 15], 9), [0, 1]);
  assert_eq!(two_sum(vec![3, 2, 4], 6), [1, 2]);
  assert_eq!(two_sum(vec![3, 3], 6), [0, 1]);
  assert_eq!(two_sum(vec![3, 2, 3], 6), [0, 2]);
  assert_eq!(two_sum(vec![-3, 4, 3, 90], 0), [0, 2]);
}