列出九宫格输入组合

题目：列出九宫格键盘输入的所有字母组合

思路：将字母的组合看成k进制的数，列出字母组合的过程即为对数进行加法运算。

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

char* letter[] = {"abc","def","ghi","jkl","mno","pqrs","tuv","wxyz"};

void listAll(char* input)
{
	int len = strlen(input);
	int total = 1;
	int i;
	for ( i=0; i<len; i++)
	{
		total = total*strlen(letter[input[i]-'0']);
	}

	for( i=0; i<total; i++)
	{
		//char item[4];
		char* item = (char*)malloc(len+1);
		int j;
		for( j=0; j<len; j++)
		{
			int size = strlen(letter[input[j]-'0']);
			int num = i;
			int index = num%size;
			num = num/size;
			item[j] = letter[input[j]-'0'][index];	
		}
		item[j] = '\0';
		printf("%s\n",item);
		
	}
}

int main()
{
	char* input = "025";
	listAll(input);

	return 0;
}