*All suggestions are welcome. Please upvote if you like it. Thank you.*

Leetcode Problem Link: 1. Two Sum

*Brute Force Solution:*

```
class Solution {
public:
vector<int> twoSum(vector<int>& nums, int target) {
//Brute Force Solution TimeO(N^2) & Auxiliary Space O(1)
int length=nums.size();
for(int i=0;i<length;i++){
for(int j=i+1;j<length;j++){
if(nums[i]+nums[j]==target){
return {i,j};
}
}
}
return {};
}
};
```

*Efficient Solution:*

```
class Solution {
public:
vector<int> twoSum(vector<int>& nums, int target){
//Efficient Solution TimeO(N) & Auxiliary Space O(N)
int length=nums.size();
unordered_map<int,int> map;
for(auto i=0;i<length;i++){
if(map.find(target-nums[i])!=map.end()){
return {i,map[target-nums[i]]};
}
map[nums[i]]=i;
}
return {};
}
};
```

*All suggestions are welcome. Please upvote if you like it. Thank you.*

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