Basic Coding Questions & Solutions

1. Smallest number in an array.

int min_element(vector <int>& arr)
{
  sort(arr.begin(),arr.end());
  return arr[0];
}

int main()
{
  vector <int> arr= {5,3,2,6,1,8,0,2,4};
  cout<<"Min element: "<< min_element(arr)<<endl;
}

2nd Method

int min_element(vector <int>& arr)
{
  int min=arr[0];
  for(int i=0;i<arr.size();i++)
  {
    if(min>arr[i])
    {
       min=arr[i];
    }
  }
  return min;
}

2. Largest number in an array

int max_element(vector <int>& arr)
{
  sort(arr.begin(),arr.end());
  return arr[arr.size()-1];
}

int main()
{
  vector <int> arr= {5,3,2,6,1,8,0,2,4};
  cout<<"Max element: "<< max_element(arr)<<endl;
}

2nd Method

int max_element(vector <int>& arr)
{
  int max=arr[0];
  for(int i=0;i<arr.size();i++)
  {
    if(max<arr[i])
    {
       max=arr[i];
    }
  }
  return max;
}

3. Reverse an array

void reverse(int arr[], int n){
  int start=0;
  int end=n-1;
  while(start<end){
    int temp=arr[start];
    arr[start]=arr[end];
    arr[end]=temp;

    start++;
    end--;
  }
}


OR (using library)


void reverse(int arr[]){
  reverse(arr.begin(),arr.end());
}

4. Count frequency of each element in an array

void countfreq(vector <int>& arr)
{
  unordered_map <int,int> freq;

  //counting freq of each element
  for(int i=0;i<arr.size();i++){
    freq[arr[i]]++;
  }
  for(auto a:freq){
    cout<<a.first<<"occured"<<a.second<<"times"<<endl;
  }
}

5. Non-repeating element in an array

void countfreq(vector <int>& arr)
{
  unordered_map <int,int> freq;

  //counting freq of each element
  for(int i=0;i<arr.size();i++){
    freq[arr[i]]++;
  }
  for(auto a:freq){
    if(freq[a]==1){
      return a;
    }
  }
}