1.Two Sum - LeeCode hashmap

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].

class Solution {
public:
    vector<int> twoSum(vector<int>& nums, int target) {
        unordered_map<int, int> map;
        for(int i=0; i<nums.capacity(); i++) {
            if(map.count(target-nums[i])) {
                return {i, map[target-nums[i]]};
            }
            map[nums[i]] = i;
        }
        return {};
    }
};