Fill a 2D array diagonally. In other words, reshape 1D array to 2D array diagonally.

fillMatrixDiagonally.cc

// An C++ example to fill a 2D array diagonally, written by AhmetCanSolak
#include <bits/stdc++.h>

int main(void){
  // Fill this array with the 1D array you want to reshape, current values are just for testing!
  std::vector<int> my_one_dimensional_array={1,2,3,4,5,6,7,8,9,10};
  
  //Calculate the required size for 2D result
  int z =1;
  while( ( ((z) * ((z)+1))/2 )  < my_one_dimensional_array.size()){
    z++;
  }
  
  //Initialize the required variables and reshape 1D array into 2D array diagonall!!!
  int my_two_dimensional_array[z][z] = {};
  bool direction=true;
  for(int a=1;a<=z;a++){
    for(int b=1;b<=z;b++){
    my_two_dimensional_array[a-1][b-1] = my_one_dimensional_array[ ( ((a+b) * ((a+b)-1))/2 - (b-1) ) - 1 ];
    }
  }
  
  //Print the result
  int upper_limit = sizeof(my_two_dimensional_array)/sizeof(my_two_dimensional_array[0]);
  for (int i = 0; i < upper_limit; i++){
    for (int j = 0; j < upper_limit; j++){
        std::cout << my_two_dimensional_array[i][j] << ' ';
    }
    std::cout << "\n";
  }
  
  return 0;
  //End of the program...
}