练习组合

/*  题目：有1、2、3、4个数字，能组成多少个互不相同且无重复数字的三位数？都是多少？	*/

#include<stdio.h>

int p(int, const int *, int);
int b(int );

int main(void)
{
	int num[4]={1, 2, 3, 4};
	int i, n;
	i = n = 0;
	for(i=123;i<=432;i++){
		if(p(i,num,4)&&b(i)){
			printf("%d\t", i);
			n++;
		}
	}
	printf("\n可以组合出%d个数\n", n);
	return 0;
}

/*判断　‘个‘， ‘十‘， ‘百‘每个位是否属于这四个数． */
int p(int cup, const int *cat, int n)
{
	int bowle, i, renum;
	while(cup>=10){
		bowle = cup%10;
		cup /= 10;
		for(i=0;i<n;i++){
			if(bowle == cat[i]){
				renum = 1;
				break;
			}
			else renum = 0;
		}
		if(renum==0) break;
	}
	return renum;
}

/*判断　个，十，百　每位都不重叠．*/
int b(int num)
{
	int bowle[3] ={0};
	int i = 0;
	while(num>=10){
		bowle[i] = num%10;
		num /= 10;
		i++;
	}
	bowle[i] = num;
	return bowle[0]!=bowle[1]&&bowle[0]!=bowle[2]&&bowle[1]!=bowle[2];
}