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#include <stdio.h>
#include <stdlib.h>
void
usage(char *argv0) {
printf("usage: %s TARGET < input.file\n", argv0);
}
int
main(int argc, char **argv) {
if (argc < 2) {
usage(*argv);
return 1;
}
int target = atoi(argv[1]);
if (target == 0) {
fprintf(stderr, "error parsing target '%s'\n", argv[1]);
return 1;
}
/* buffer for each line */
char buf[100] = {'\0'};
size_t nums_len = 200;
int *nums = malloc(sizeof(int) * nums_len);
if (nums == NULL) {
perror("malloc");
return 1;
}
int *n = nums;
while (fgets(buf, 100, stdin) != NULL) {
*n++ = atoi(buf);
size_t offset = n - nums;
if (offset > nums_len) {
nums_len += 10;
int *tmp = realloc(nums, sizeof(int) * nums_len);
if (tmp == NULL) {
perror("realloc");
goto error_free_nums;
}
nums = tmp;
n = nums + offset;
}
}
for (size_t i = 0; i < nums_len; i++) {
for (size_t j = i + 1; j < nums_len; j++) {
if (nums[i] + nums[j] == target) {
printf("%d * %d = %d\n", nums[i], nums[j], nums[i] * nums[j]);
goto end;
}
}
}
end:
free(nums);
return 0;
error_free_nums:
free(nums);
return 1;
}
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