输出全组合问题

1. 网易：题意很简单，写一个程序，打印出以下的序列。
   (a),(b),(c),(d),(e)........(z)
   (a,b),(a,c),(a,d),(a,e)......(a,z),(b,c),(b,d).....(b,z),(c,d).....(y,z)
   (a,b,c),(a,b,d)....(a,b,z),(a,c,d)....(x,y,z)
   ....
   (a,b,c,d,.....x,y,z)（思路：全组合问题）

#include "stdafx.h"#include <iostream>using namespace std;#define TABLE_LEN 26char a_table[TABLE_LEN];char pstr[TABLE_LEN];int current = 0;bool pick_array(char *table, int pick_len, int len){if (table == NULL)return false;else if(pick_len == 0 || len == 0){pstr[current] = '\0';printf("(%s),", pstr);return true;}for (int i = 0; i < len - pick_len + 1; i++){pstr[current++] = table[i];if (!pick_array(table + i + 1, pick_len - 1, len - i - 1))return false;current--;}return true;}int _tmain(int argc, _TCHAR* argv[]){for (int i = 0; i < TABLE_LEN; i++){a_table[i] = 'a' + i;}for (int len = 1; len <= TABLE_LEN; len++){current = 0;pstr[current] = '\0';if (!pick_array(a_table, len, TABLE_LEN)){printf("error\n");return -1;}printf("\n");}std::cin.get();return 0;}

取abcde做测试