make sample input file for deterministic selection

sample.c

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

#ifdef _WIN32
#define fileopen(fp, filename, type) fopen_s(&fp, filename, type)
#define fscanf fscanf_s
#else
#define fileopen(fp, filename, type) fp = fopen(filename, type)
#endif

#define LENGTH 1000 // > 30
#define TIPSIZE 31 // > 5
#define CASES 20

int array[LENGTH] = {14, 57, 24, 6, 37, 32, 2, 43, 30, 25, 23, 52, 12, 63, 3, 5, 44, 17, 34, 64, 10, 27, 48, 8, 19, 60, 21, 1, 55, 41, 29, 11, 58, 39};
int subarray[LENGTH];
FILE *ofp, *smp;

inline void swap(int *p, int *q) {
	int temp;
	temp = *p; *p = *q; *q = temp;
}

// selection sort
void sort(int *array, int start, int size) {
	int i, j;

	for (i = 0; i < size - 1; i++) {
		int min = array[start + i];
		int minp = i;
		for (j = i + 1; j < size; j++) {
			if (min > array[start + j]) {
				min = array[start + j];
				minp = j;
			}
		}

		if (minp != i)
			swap(&array[start + i], &array[start + minp]);
	}

	return ;
}

int main() {
	int loop = 0;
	int size, find, tip;

	srand(time(0));

	fileopen(ofp, "input.txt", "w");
	fileopen(smp, "sample.txt", "w");

	fprintf(ofp, "%d\n", CASES);

	find = 7;
	size = 34;
	tip  = 5;
	while (++loop <= CASES) {
		int i, j;
		int hint;

		if (loop > 1) {
			size = rand() % (LENGTH - 30) + 30;
			find = rand() % (size - 1) + 1;
			tip  = rand() % (TIPSIZE - 5) + 5;
			//tip  = (tip / 2) * 2 + 1; // make odd number
		}

		fprintf(ofp, "%d %d %d\n", find, size, tip);

		for (i = 0; i < size; i++) {
			if (loop > 1) array[i] = rand() % LENGTH + 1;
			fprintf(ofp, "%d ", array[i]);
		}
		fprintf(ofp, "\n");


		{
			int set_count = (size - 1) / tip + 1;
			int hint_count = set_count - 1;

			for (i = 0; i < set_count - 1; i++) {
				sort(array, i * tip, tip);
				subarray[i] = array[i * tip + (tip / 2)];
			}
			sort(array, i * tip, (size - 1) % tip + 1);
			
			if ((size - 1) % tip + 1 >= tip / 2 + 1) {
				subarray[i] = array[i * tip + (tip / 2)];
				hint_count++;
			}

			sort(subarray, 0, hint_count);
			hint = subarray[hint_count / 2];
		}

		sort(array, 0, size);
		fprintf(smp, "#%d %d %d\n", loop, array[find - 1], hint);
		printf("#%d %d %d, k=%d, n=%d, a=%d\n", loop, array[find - 1], hint, find, size, tip);
	}

	return 0;
}