What is the most efficient way to create a multidimensional integer array in C++ or Java?

[SubhanUllah]

#include <vector> 
#include <mdspan> 
#include <print> 
  
int main() 
{ 
  std::vector v = {1,2,3,4,5,6,7,8,9,10,11,12}; 
  
  // View data as contiguous memory representing 2 rows of 6 ints each 
  auto ms2 = std::mdspan(v.data(), 2, 6); 
  // View the same data as a 3D array 2 x 3 x 2 
  auto ms3 = std::mdspan(v.data(), 2, 3, 2); 
  
  // write data using 2D view 
  for(size_t i=0; i != ms2.extent(0); i++) 
    for(size_t j=0; j != ms2.extent(1); j++) 
      ms2[i, j] = i*1000 + j; 
  
  // read back using 3D view 
  for(size_t i=0; i != ms3.extent(0); i++) 
  { 
    std::println("slice @ i = {}", i); 
    for(size_t j=0; j != ms3.extent(1); j++) 
    { 
      for(size_t k=0; k != ms3.extent(2); k++) 
        std::print("{} ",  ms3[i, j, k]); 
      std::println(""); 
    } 
  } 
}