Unexpected output at a particular row for a dynamic 2D array - c

Question

I was solving a programing question for displaying Pascal triangle. In the code, I have set the last element of every row equal to zero. Still, the 6th row produces the output as 50 for the last element. I'm unable to figure out the reason for this. Kindly help. The code is attached.
int ** generate(int A, int *number_of_rows) {
*number_of_rows = A;
int i,j,nc=0;
int **result = (int**)malloc(A * sizeof(int *));
for(i=0;i<A;i++)
{
nc=i+1;
result[i]=(int)malloc(nc*sizeof(int));
result[i][0]=nc;
result[i][1] = 1;
for(j=2;j<nc;j++)
{
result[i][j]=result[i-1][j]+result[i-1][j-1];
}
}
return result;
}
Edit:
The first element of every row displays the number of columns in that row.

Answer 1

#include <stdio.h>
#include <stdlib.h>
int ** generate(int A, int *number_of_cols) {
int **result = malloc(A * sizeof(int *));
int nc;//number of columns
for(int i = 0; i < A; ++i){
number_of_cols[i] = nc = i + 1;
result[i] = malloc(nc * sizeof(int));
result[i][0] = result[i][nc-1] = 1;
if(i > 1)
for(int j = 1; j < nc -1; ++j){
result[i][j] = result[i-1][j-1] + result[i-1][j];
}
}
return result;
}
int main(void){
int n;
scanf("%d", &n);
int *number_of_cols = malloc(n * sizeof(int));
int **pascal_triangle = generate(n, number_of_cols);
for(int i = 0; i < n; ++i){
printf("%*s", 2 * (n-i-1), "");
for(int j = 0; j < number_of_cols[i]; ++j){
printf("%4d", pascal_triangle[i][j]);
}
puts("");
free(pascal_triangle[i]);
}
free(pascal_triangle);
free(number_of_cols);
return 0;
}

Answer 2

I can't understand the purpose of passing the *number_of_row just to assign it the other parameter address. However, I'd split your main for loop in 2:
one to allocate all memory and another to fill it.
for(i=0;i<A;i++)
result[i]=(int)malloc((i+1)*sizeof(int));
result[0][0]=1; //in your code, result[i-1] was accessed with i=0
for(i=1;i<A;i++) {
result[i][0] = i+1;
result[i][1] = 1;
for(j=2;j<i;j++)
result[i][j] = result[i-1][j] + result[i-1][j-1]; //when j reaches the last value,
//[i-1][j] won't work! So put j<i instead.
result[i][j] = 1;
}
The rest of code was OK, check if this is what you wanted. The resulting triangle shoud be:
1
2 1
3 1 1
4 1 2 1
5 1 3 3 1
6 1 4 6 4 1 etc.