class Solution {
public:
vector<int> getConcatenation(vector<int>& nums) {
int n=nums.size();
vector<int> ans(2*n);
for(int i=0;i<2*n;i++)
{
if(i<n)
{
ans.push_back(nums[i]);
}
else
{
ans.push_back(nums[i-n]);
}
}
return ans;
}
};
This above code is not giving appropriate ans.
while below code is working fine.
class Solution {
public:
vector<int> getConcatenation(vector<int>& nums) {
int n=nums.size();
vector<int> ans(2*n);
for(int i=0;i<2*n;i++)
{
if(i<n)
{
ans[i]=nums[i];
}
else
{
ans[i]=nums[i-n];
}
}
return ans;
}
};
When you create the vector you have specified a size already (usually not done with vectors) so your vector already filled with ints that have been set to 0. So when you use ans[i] = nums[i]; you are simply editing one of the already existing elements stored in the vector.
Usually when you create a vector you create it as an empty one by doing vector<int> ans; or vector<int>* ans = new vector<int>(); (if you want to create it on the heap) and then add a new element to it using ans.push_back(value); which will add the element to the back/end of the vector.