problem

Given an array of integers, return indices of the two numbers such that they add up to a specific target.
You may assume that each input would have exactly one solution, and you may not use the same element twice.

Example

Given nums = [2, 7, 11, 15], target = 9,
Because nums[0] + nums[1] = 2 + 7 = 9,
return [0, 1].

Solution

use std::collections::HashMap;
impl Solution {
    pub fn two_sum(nums: Vec<i32>, target: i32) -> Vec<i32> {
        let mut mm: HashMap<i32, i32> = HashMap::new();
        for (i, v) in nums.iter().enumerate() {
            match mm.get(&(target-v)) {
                Some(&index) => { return vec![index, i as i32]; }
                None => { mm.entry(*v).or_insert(i as i32); }
            }
        }
        vec![]
    }
}

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