【2】1. Two Sum

1. Two Sum

• Total Accepted: 409869
• Total Submissions: 1347018
• Difficulty: Easy
• Contributors: Admin

 

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> hash;
        vector<int> result;
        for(int i = 0; i < nums.size(); i++){
            if(hash.find(target - nums[i]) != hash.end()){
                result.push_back(hash[target - nums[i]]);
                result.push_back(i);
                return result;
            }
            hash[nums[i]] = i;
        }
        result.push_back(-1);
        result.push_back(-1);
        return result;
    }
};