ch6

8q.c

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

int counter = 0;

int abs(int val){
	return val < 0? val * -1: val;
}

void draw(int * array, int size){
	int i;
	for(i = 0; i < size; i++){
		printf("%d\t", *(array + i));
	}
	printf("\n");
}

void check(int size, int time, int * position){
	int i, j, ok = 1, * copy;
	for(i = 0; i < size; i++){
		ok = 1;
		for(j = 0; j < size - time; j++){
			if(abs(i - *(position + j)) == abs(size - time - j) || *(position + j) == i){
				ok = 0;
			}
		}
		if(ok){
			copy = malloc(sizeof(int) * size);
			
			for(j = 0; j < size; j++){
				*(copy + j) = *(position + j);
			}

			*(copy + size - time) = i;
			if(time == 1){
				draw(copy, size);
				counter++;
			}else{
				check(size, time - 1, copy);
			}

			free(copy);
		}
	}
}

void run(int size){
	int position[size], i;
	for(i = 0; i < size; i++){
		position[i] = -1;
	}
	check(size, size, position);
}

void main(){
	run(8);
	printf("%d\n", counter);
}