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#include <stdbool.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#define INPUT_LEN 1000
#define SEARCH_LEN 25
bool has_sum(uint64_t *cur_num)
{
uint64_t search = *cur_num;
uint64_t *p1 = cur_num - SEARCH_LEN;
do {
uint64_t *p2 = cur_num - SEARCH_LEN;
do {
if (*p1 + *p2 == search) {
return true;
}
} while (++p2 < cur_num);
} while (++p1 < cur_num);
return false;
}
int exe_program(const char *filename)
{
FILE *file = fopen(filename, "r");
// Include space for newline and string terminator
char buffer[24] = { 0 };
uint64_t nums[INPUT_LEN];
size_t num_size = 0;
while (fgets(buffer, 24, file)) {
nums[num_size++] = strtoull(buffer, NULL, 10);
}
fclose(file);
uint64_t *cur_num = nums + SEARCH_LEN;
do {
if (!has_sum(cur_num)) {
return *cur_num;
}
} while (++cur_num < nums + num_size);
return -1;
}
int main(int argc, char *argv[])
{
printf("%i\n", exe_program(argv[argc - 1]));
}
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