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/**
* Return an array of size *returnSize.
* Note: The returned array must be malloced, assume caller calls free().
*/
void helper(char **result, char *map[10], char *digits, char *tmp, int index, int *returnSize)
{
char *p = map[*digits - '0'];
for(; *p; ++p) {
tmp[index] = *p;
helper(result, map, digits + 1, tmp, index + 1, returnSize);
}
if(*digits == '\0') {
*(result + *returnSize) = malloc(sizeof(char) * index + 1);
for(int i = 0; i < index; i++) {
*(*(result + *returnSize) + i) = tmp[i];
}
*(*(result + *returnSize) + index) = '\0';
++*returnSize;
}
}
char** letterCombinations(char* digits, int* returnSize) {
int len = strlen(digits);
int index = 0;
char tmp[len + 1];
char **result = malloc(sizeof(int *) * 100);
char *map[10] = {
" ", " ", "abc", "def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz"
};
*returnSize = 0;
if(len < 1)
return result;
while(*digits) {
if(*digits >= '2' && *digits <= '9') {
helper(result, map, digits, tmp, index, returnSize);
} else {
*returnSize = 0;
break;
}
++digits;
}
return result;
}
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