17. 电话号码的字母组合c

/**
 * Note: The returned array must be malloced, assume caller calls free().
 */
char temp[10];
char c[10][5]={" "," ","abc","def","ghi","jkl","mno","pqrs","tuv","wxyz"};

void dfs(char** array,char* digits,int* returnSize,int n,int index,int count){
    if(index>n) return ;
    if(index==n){
        array[*returnSize]=(char*)malloc(sizeof(char)*(count+1));
        for(int i=0;i<count;i++) array[*returnSize][i]=temp[i];
        array[*returnSize][count]=0;
        (*returnSize)++;
        return;
    }
    int t=digits[index]-'0';
    int i=0;
    while(c[t][i]!=0){
        temp[count]=c[t][i++];
        dfs(array,digits,returnSize,n,index+1,count+1);
    }
}

char** letterCombinations(char* digits, int* returnSize) {
    int n=strlen(digits);
    char** array=(char**)malloc(sizeof(char*)*100000);
    *returnSize=0;
    dfs(array,digits,returnSize,n,0,0);
    if(n==0) (*returnSize)=0;
    return array;
}