use std::collections::HashMap;

pub fn two_sum(nums: Vec<i32>, target: i32) -> Vec<i32> {
    let mut visited = HashMap::with_capacity(nums.len());

    for (num, i) in nums.into_iter().zip(0..) {
        let pair = target - num;
        match visited.get(&pair) {
            Some(j) => return vec![i, *j],
            None => {
                visited.insert(num, i);
            },
        }
    }

    panic!("no solution")
}


fn main() {
    dbg!(two_sum(vec![2, 7, 11, 15], 9));
}