Merge Sort (merge)

merge.cpp

/*
  Merge array

  @param f_s : first_start
  @param f_e : first_end
  @param s_s : second_start
  @param s_e : second_end
  @param source : source array
*/
void merge(int f_s, int f_e, int s_s, int s_e, int* source) {
  int size = (s_e - f_s) + 1;  // Merged array capacity
  int* temp = new int[size];

  int temp_index, first_index, second_index;
  for (temp_index = 0, first_index = f_s, second_index = s_s;
       first_index <= f_e && second_index <= s_e;) {
    if (source[first_index] < source[second_index]) {
      temp[temp_index] = source[first_index];
      first_index++;
    } else {
      temp[temp_index] = source[second_index];
      second_index++;
    }
    temp_index++;  // Pointed next array index
  }

  while (first_index <= f_e) {
    temp[temp_index] = source[first_index];
    first_index++;
    temp_index++;
  }

  while (second_index <= s_e) {
    temp[temp_index] = source[second_index];
    second_index++;
    temp_index++;
  }

  for (int source_index = f_s, temp_index = 0; source_index <= s_e;
       source_index++, temp_index++) {
    source[source_index] = temp[temp_index];
  }
  delete[] temp;
}