C++ Solution for Two Sum Problem with Explanation

The given code is a solution to the Two Sum problem in C++. \n\nThe function `twoSum` takes in a vector `nums` and an integer `target` as input and returns a vector containing the indices of the two numbers that add up to the target. \n\nThe function uses an unordered map `hashtable` to store the numbers in the vector and their corresponding indices. It iterates through the vector, for each number it checks if the complement of the current number (target - nums[i]) is present in the hashtable. If it is, it returns the indices of the two numbers. If not, it adds the current number and its index to the hashtable. \n\nIf no solution is found, an empty vector is returned. \n\nThere is a typo in the code. The semicolon (;) after the closing curly brace of the function should be removed.