Two Sum
Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target.
Solution
brute-force
class Solution {
public:
vector<int> twoSum(vector<int>& nums, int target) {
for(int i=0; i < nums.size(); ++i)
{
int left = target - nums[i];
for(int j=i+1; j < nums.size(); j++)
{
if(nums[j] == left)
{
return {i, j};
}
}
}
return {};
}
};
hashmap
class Solution {
public:
vector<int> twoSum(vector<int>& nums, int target) {
unordered_map<int, int> indices;
for(int i=0; i < nums.size(); ++i )
{
indices[nums[i]] = i;
}
for(int i=0; i < nums.size(); ++i)
{
int left = target - nums[i];
if(indices.count(left) && indices[left] != i)
{
return {i, indices[left]};
}
}
return {};
}
}
