是否有算法打印阵列的所有子序列？

如果有任何问题请告诉我.

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

int main(void) 
{
   char str[] = "1234"; 
   size_t len = strlen(str);                 // Array length (in elements)
   char *A = malloc(sizeof(char) * len);
   strcpy(A,str);

   size_t elbp = (1<<len) - 1;             // Element selection bit pattern
   size_t i,j;                            // Iterators
   int a = 0,b = 0,n = 0;
   char **arr = malloc(sizeof(char*) * (10000));      //allocating memory

if (A[0] >= 'A' && A[0] <= 'Z')          //If the string given is "ABCD...." transfer 'A' to '1' ; 'C' to '3' ...etc
    for(int i = 0; i < len; i++)
        A[i] = A[i] - 'A' + '1';

// Cycle through all the bit patterns
for (i = 1; i<=elbp; i++)
{
    arr[b] = malloc(sizeof(char) * len);

    // For each bit pattern,store in arr[b] the 'checked' elements
    for (j = 0,a = 0; j < len; j++) 
        if (i & (1<<j))
            arr[b][a++] = A[j]; 
    b++;
}

int *num = calloc(sizeof(int),10000);

for (i = 0; i < b; i++) 
    num[i] = strtol(arr[i],NULL,10);     //convert char to int

for (i = 0; i < b; i++)                   //sort array numbers from smallest to largest
    for (a = 0; a < i; a++)
        if (num[i] < num[a])
        {
            n = num[i];
            num[i] = num[a];
            num[a] = n;
        }

char *result = calloc(sizeof(char),10000);

for (i = 0,a = 0; i<b; i++)
    a += sprintf(&result[a],"%d,",num[i]);     //convert int to char and store it in result[a]

result[a - 1] = '';    //remove the last ','
len = strlen(result);

if (str[0] >= 'A' && str[0] <= 'Z')              //if the string given is "ABCD..." transfer '1' to 'A' ; '12' to 'AB' ; '13' to 'AC'.....etc
    for (i = 0; i < len; i++)
        if(result[i] != ',')
            result[i] = 'A' + (result[i] - '1') ;

  ///test
  printf("%s",result);

  return 0;
}

“1234”的输出：

1,1234

“123456789”的输出：

1,5,6,7,8,9,15,16,17,18,19,25,26,27,28,29,35,36,37,38,39,45,46,47,48,49,56,57,58,59,67,68,69,78,79,89,125,126,127,128,129,135,136,137,138,139,145,146,147,148,149,156,157,158,159,167,168,169,178,179,189,235,236,237,238,239,245,246,247,248,249,256,257,258,259,267,268,269,278,279,289,345,346,347,348,349,356,357,358,359,367,368,369,378,379,389,456,457,458,459,467,468,469,478,479,489,567,568,569,578,579,589,678,679,689,789,1234,1235,1236,1237,1238,1239,1245,1246,1247,1248,1249,1256,1257,1258,1259,1267,1268,1269,1278,1279,1289,1345,1346,1347,1348,1349,1356,1357,1358,1359,1367,1368,1369,1378,1379,1389,1456,1457,1458,1459,1467,1468,1469,1478,1479,1489,1567,1568,1569,1578,1579,1589,1678,1679,1689,1789,2345,2346,2347,2348,2349,2356,2357,2358,2359,2367,2368,2369,2378,2379,2389,2456,2457,2458,2459,2467,2468,2469,2478,2479,2489,2567,2568,2569,2578,2579,2589,2678,2679,2689,2789,3456,3457,3458,3459,3467,3468,3469,3478,3479,3489,3567,3568,3569,3578,3579,3589,3678,3679,3689,3789,4567,4568,4569,4578,4579,4589,4678,4679,4689,4789,5678,5679,5689,5789,6789,12345,12346,12347,12348,12349,12356,12357,12358,12359,12367,12368,12369,12378,12379,12389,12456,12457,12458,12459,12467,12468,12469,12478,12479,12489,12567,12568,12569,12578,12579,12589,12678,12679,12689,12789,13456,13457,13458,13459,13467,13468,13469,13478,13479,13489,13567,13568,13569,13578,13579,13589,13678,13679,13689,13789,14567,14568,14569,14578,14579,14589,14678,14679,14689,14789,15678,15679,15689,15789,16789,23456,23457,23458,23459,23467,23468,23469,23478,23479,23489,23567,23568,23569,23578,23579,23589,23678,23679,23689,23789,24567,24568,24569,24578,24579,24589,24678,24679,24689,24789,25678,25679,25689,25789,26789,34567,34568,34569,34578,34579,34589,34678,34679,34689,34789,35678,35679,35689,35789,36789,45678,45679,45689,45789,46789,56789,123456,123457,123458,123459,123467,123468,123469,123478,123479,123489,123567,123568,123569,123578,123579,123589,123678,123679,123689,123789,124567,124568,124569,124578,124579,124589,124678,124679,124689,124789,125678,125679,125689,125789,126789,134567,134568,134569,134578,134579,134589,134678,134679,134689,134789,135678,135679,135689,135789,136789,145678,145679,145689,145789,146789,156789,234567,234568,234569,234578,234579,234589,234678,234679,234689,234789,235678,235679,235689,235789,236789,245678,245679,245689,245789,246789,256789,345678,345679,345689,345789,346789,356789,456789,1234567,1234568,1234569,1234578,1234579,1234589,1234678,1234679,1234689,1234789,1235678,1235679,1235689,1235789,1236789,1245678,1245679,1245689,1245789,1246789,1256789,1345678,1345679,1345689,1345789,1346789,1356789,1456789,2345678,2345679,2345689,2345789,2346789,2356789,2456789,3456789,12345678,12345679,12345689,12345789,12346789,12356789,12456789,13456789,23456789,123456789

“ABCDEF”的输出：

A,E,F,AE,AF,BE,BF,CE,CF,DE,DF,EF,ABC,ABD,ABE,ABF,ACD,ACE,ACF,ADE,ADF,AEF,BCD,BCE,BCF,BDE,BDF,BEF,CDE,CDF,CEF,DEF,ABCD,ABCE,ABCF,ABDE,ABDF,ABEF,ACDE,ACDF,ACEF,ADEF,BCDE,BCDF,BCEF,BDEF,CDEF,ABCDE,ABCDF,ABCEF,ABDEF,ACDEF,BCDEF,ABCDEF