Two Sum

Desicription

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:

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Given nums = [2, 7, 11, 15], target = 9,
Because nums[0] + nums[1] = 2 + 7 = 9,
return [0, 1].

Solution

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class Solution{
public:
vector<int> twoSum(vector<int> &numbers, int target)
{
unordered_map<int, int>mp;
for(int i = 0; i < numbers.size(); i++){
int need = target - numbers[i];
if(mp.find(need) != mp.end()){
vector<int>res;
res.push_back(i);
res.push_back(mp[need]);
return res;
}
mp[numbers[i]] = i;
}
}
};