求多数组的排列组合算法

递归

public List<String> permutation(List<String> inputList){
    List<String> resList = new ArrayList<>();
    permutationInt(inputList, resList, 0, 
            new char[inputList.size()]);
    return resList;
}
private void permutationInt(List<String> inputList, List<String> resList,
        int ind, char[] arr) {
    if(ind == inputList.size()){
        resList.add(new String(arr));
        return;
    }

    for(char c: inputList.get(ind).toCharArray()){
        arr[ind] = c;
        permutationInt(inputList, resList, ind + 1, arr);
    } 
}