#include <stdio.h>

int gcd(int a, int b, int level);

int main()
{
    int n1, n2;
    printf("\n*** 求二數的最大公因數 ***\n\n請輸入兩個正整數 ==> ");
    scanf("%d %d",&n1,&n2);

    printf("\n輸入的二個正整數分別是%d與%d，遞迴呼叫層級及回傳值如下...\n\n",n1,n2); 
    gcd(n1,n2,0);

    printf("\n");
    
	return 0;
} 

int gcd(int a, int b, int level)
{
	int i, result;
	 
	level++;
	for (i = 1; i < level; i++) printf("\t");
	if (b == 0) {
		printf("gcd(%d,%d) = %d [解*]\n",a,b,a);
	    return(a);
	}
	else {
	    printf("gcd(%d,%d)\n",a,b);
	    result = gcd(b,a%b,level);
	    for (i = 1; i < level; i++) printf("\t");
	    printf("gcd(%d,%d) = %d\n",a,b,result);
	    return(result);
	}
}