Dynamic Memory Allocation For 2D Array

#include <stdio.h>
#include <stdlib.h>

void swap(int *a, int *b);

int main()
{
    int **x, n, i, j;

    printf("How many numbers?\n");
    scanf("%d", &n);
    x = (int **) malloc(n*sizeof(int *));

    for(i = 0; i < n; i++)
        x[i] = (int *) malloc((i+1)*sizeof(int));

    for(i = 0; i < n; i++)
        for(j = 0; j <= i; j++)
            x[i][j] = i + j;

    for(i = 0; i < n; i++)
    {
        for(j = 0; j <= i; j++)
            printf("%d ", x[i][j]);
        printf("\n");
    }

    for(i = 0; i < n; i++)
        free(x[i]);

    free(x);

    return 0;
}

void swap(int *a, int *b)
{
    int temp = *a;
    *a = *b;
    *b = temp;
}