Two sum

Leetcode c++ solution

Question Link

https://leetcode.com/problems/two-sum/

Question

Approach

1. Brute Force

We can check the pairs that sum to target in O(n2) by running two for loops and by checking them.

2. Another method will be using Hashmap

vector<int> twoSum(vector<int>& nums, int target) {
map<int,int> m;
vector<int> v;
for(int i=0;i<nums.size();i++)
{

m[nums[i]]++;

}

if(m.find(target-nums[i])!=m.end())
{
v.push_back(m[target-nums[i]]);
v.push_back(i);
return v;
}

m[nums[i]]=i;
}
return v;

}

Time Complexity =O(n)

Thank you:)