两数之和

  1. use std::collections::HashMap;
  2. use std::convert::TryInto;
  4. // Given an array of integers nums and an integer target,
  5. // return indices of the two numbers such that they add up to target.
  7. pub fn two_sum(nums: Vec<i32>, target: i32) -> Vec<i32> {
  8.     let mut hash_map: HashMap<i32, i32> = HashMap::new();
  10.     for (i, item) in nums.iter().enumerate() {
  11.         match hash_map.get(&(target - item)) {
  12.             Some(value) => {
  13.                 return vec![i.try_into().unwrap(), *value];
  14.             }
  15.             None => {
  16.                 hash_map.insert(*item, i.try_into().unwrap());
  17.             }
  18.         }
  19.     }
  21.     vec![]
  22. }
  24. #[cfg(test)]
  25. mod test {
  26.     use super::*;
  28.     #[test]
  29.     fn test() {
  30.         let nums = vec![2, 7, 11, 15];
  31.         assert_eq!(two_sum(nums, 9), vec![1, 0]);
  33.         let nums = vec![3, 2, 4];
  34.         assert_eq!(two_sum(nums, 6), vec![2, 1]);
  36.         let nums = vec![3, 3];
  37.         assert_eq!(two_sum(nums, 6), vec![1, 0]);
  38.     }
  39. }