LE PROBLÈME DES 8 DAMES (14 CAVALIERS, ...)

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


typedef struct {
	int x, y;
} cases;

typedef struct {
	char c[8][8];
} echiquier;

int myabs(int a){
	return (a>=0)?a:-a;
}

int damesCanGo(cases a, cases b){
	if (a.x==b.x || a.y==b.y){
		return 1;
	}else if (myabs(a.x-b.x) == myabs(a.y-b.y)){
		return 1;
	}else{
		return 0;
	}
}
int fousCanGo(cases a, cases b){
	if (myabs(a.x-b.x) == myabs(a.y-b.y)){
		return 1;
	}else{
		return 0;
	}
}
int cavaliersCanGo(cases a, cases b){
	int c, d;
	c=myabs(a.x-b.x);
	d=myabs(a.y-b.y);
	if ((d==2 && c==1) || (d==1 && c==2)){
		return 1;
	}else{
		return 0;
	}
}
int roisCanGo(cases a, cases b){
	int c, d;
	c=myabs(a.x-b.x);
	d=myabs(a.y-b.y);
	if (c==1 && d==1){
		return 1;
	}else{
		return 0;
	}
}
void afficher(echiquier a){
	int i, j;
	for (j=0;j<10;j++){
		printf("----");
	}
	printf("\n");
	for (i=0;i<8;i++){
		for (j=0;j<8;j++){
			printf(" | %c", a.c[i][j]);
		}
		printf(" |\n");
		for (j=0;j<10;j++){
			printf("----");
		}
		printf("\n");
	}
}
int sol(int nbr, int di, int dj, echiquier a, int (*fnc) (cases a, cases b)){
	int i, j, k, l, m, n=0;
	cases c, b;
	if (nbr==0){
		//afficher(a);
		return 1;
	}
	nbr--;
	for (i=di;i<8;i++){
		for (j=dj;j<8;j++){
			if (a.c[i][j]==' '){
				m=0;
				for (k=0;k<=di;k++){
					for (l=0;l<8;l++){
						if ((k!=i || l!=j ) && a.c[k][l]=='Q'){
							c.x=i;
							c.y=j;
							b.x=k;
							b.y=l;
							if (fnc(c, b)){
								m=1;
								break;
							}
						}
					}
					if (m) break;
				}
				if (!m){
					a.c[i][j]='Q';
					n+=sol(nbr, i, j, a, fnc);
					a.c[i][j]=' ';
				}
			}
		}
		dj=0;
	}
	return n;
}
echiquier new_echiquier(){
	echiquier a;
	int i, j;
	for (i=0;i<8;i++){
		for (j=0;j<8;j++){
			a.c[i][j]=' ';
		}
	}
	return a;
}
int main(){
	echiquier a=new_echiquier();
	printf ("il y a %d solutions au problÚme des 8 dames!\n",sol(8, 0, 0, a, damesCanGo));
	printf ("il y a %d solutions au problÚme des 14 fous!\n",sol(14, 0, 0, a, fousCanGo));
	printf ("il y a %d solutions au problÚme des 32 cavaliers!\n",sol(32, 0, 0, a, cavaliersCanGo));
	printf ("il y a %d solutions au problÚme des 16 rois!\n",sol(16, 0, 0, a, roisCanGo));
	return 42;
}