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#!/usr/bin/env cscript
/* SPDX-License-Identifier: GPL-2.0
*
* Copyright (C) 2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
*/
#define _GNU_SOURCE
#include <stdint.h>
#include <stddef.h>
#include <stdlib.h>
#include <stdio.h>
#include <inttypes.h>
#include <errno.h>
enum { PASCALS_TRIANGLE_MAX_ROWS_FOR_UINT64 = 68 };
static uint64_t **create_pascals_triangle(size_t num_rows)
{
uint64_t **triangle;
size_t i, j;
if (!num_rows || num_rows > PASCALS_TRIANGLE_MAX_ROWS_FOR_UINT64) {
errno = EINVAL;
return NULL;
}
triangle = reallocarray(NULL, num_rows + 1, sizeof(*triangle));
if (!triangle)
return NULL;
triangle[num_rows] = NULL;
for (i = 0; i < num_rows; ++i) {
triangle[i] = reallocarray(NULL, i + 1, sizeof(**triangle));
if (!triangle[i]) {
for (j = 0; j < i; ++j)
free(triangle[j]);
free(triangle);
return NULL;
}
triangle[i][0] = triangle[i][i] = 1;
for (j = 1; j < i; ++j)
triangle[i][j] = triangle[i - 1][j - 1] + triangle[i - 1][j];
}
return triangle;
}
static void free_pascals_triangle(uint64_t **triangle)
{
size_t i;
if (!triangle)
return;
for (i = 0; triangle[i]; ++i)
free(triangle[i]);
free(triangle);
}
static void print_pascals_triangle(FILE *file, uint64_t **triangle)
{
size_t i, j;
for (i = 0; triangle[i]; ++i) {
for (j = 0; j < i + 1; ++j)
fprintf(file, "%" PRIu64 " ", triangle[i][j]);
fputc('\n', file);
}
}
int main(int argc, char *argv[])
{
uint64_t **triangle;
size_t num_rows;
char *endptr;
if (argc != 2) {
fprintf(stderr, "Usage: %s ROWS\n", argv[0]);
return 1;
}
num_rows = strtoul(argv[1], &endptr, 10);
if (!*argv[1] || *endptr) {
fprintf(stderr, "ERROR: `%s' is not a valid number\n", argv[1]);
return 1;
}
triangle = create_pascals_triangle(num_rows);
if (!triangle) {
perror("ERROR: unable to create triangle");
return 1;
}
print_pascals_triangle(stdout, triangle);
free_pascals_triangle(triangle);
return 0;
}
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