16.10.cpp

#include <iostream>
#include <malloc.h>
using namespace std;

int** My2DAlloc(int rows, int cols){
    int **arr = (int**)malloc(rows*sizeof(int*));
    for(int i=0; i<rows; ++i)
        arr[i] = (int*)malloc(cols*sizeof(int));
    return arr;
}
int** My2DAlloc1(int rows, int cols){
    int header = rows * sizeof(int*);
    int data = rows * cols * sizeof(int);
    int **arr = (int**)malloc(header + data);
    int *buf = (int*)(arr + rows);
    for(int i=0; i<rows; ++i)
        arr[i] = buf + i * cols;
    return arr;
}
int main(){
    int **arr = My2DAlloc1(4, 5);
    arr[2][3] = 23;
    cout<<arr[2][3]<<endl;
    return 0;
}