这是RainbowCrack作者的MATLAB函数：
function ret = calc_success_probability(N, t, m)
arr = zeros(1, t - 1);
arr(1) = m;
for i = 2 : t - 1
arr(i) = N * (1 - (1 - 1 / N) ^ arr(i - 1));
end
exp = 0;
for i = 1 : t - 1
exp = exp + arr(i);
end
ret = 1 - (1 - 1 / N) ^ exp;
给定一个彩虹表，其中包含键空间N，大的无符号整数，长度为t的链和链数为m的情况下，它计算找到明文密码成功的概率。
示例运行：
calc_success_probability(80603140212, 2400, 40000000)
返回0.6055。
我很难将其转换为Python。在Python 3中，不再有最大整数，因此N不再是问题。我认为在计算中，我必须将所有内容强制设置为较大的浮点数，但我不确定。
我也不知道MATLAB中的运算顺序。我认为代码是这样说的：
创建大小为[1 .. 10]的数组，以便十个元素 用零初始化该数组的每个元素
在基于零的索引中，我认为这将是array[0 .. t-1]，看起来MATLAB会将1用作第一个（第0个）索引。
然后将数组（基于0的索引）的第二个元素初始化为m。
对于数组中的每个元素，将pos=1（从0开始的索引）到t-1：
array[pos] = N * (1 - (1 - 1/N) ** array[pos-1]
其中**是幂运算符。我认为幂在MATLAB中是^，因此N * (1 - (1-1/N)的{{1}}就像上面的幂。
然后设置一个指数。对于数组0到array[pos-1]中的每个元素：
指数是指数+ 1
返回概率= t-1的幂次；
我的Python代码如下所示，并且不起作用。我不知道为什么，但是可能是因为我对MATLAB或Python的理解不够，或者我以某种方式读错了数学，而MATLAB中发生的事情并不是我所期望的，即我的操作顺序和/或类型错误，无法正常工作，而我在这些方面缺少某些东西...
1 - (1 - 1/N)答案 0 :(得分：2)
注意括号！您已经翻译了：
public class ProductAdapter extends RecyclerView.Adapter<ProductAdapter.ProductViewHolder> {
private Map<Integer, Integer> mSpinnerSelectedItem = new HashMap<Integer, Integer>();
//this context we will use to inflate the layout
//Remove this..Please
// CheckBox checkBox;
//private Context mCtx;
private SearchableSpinner spinner;
//we are storing all the products in a list
private List<Product> productList;
private Activity create;
public ProductAdapter(Activity activity) {
create = activity;
}
//getting the context and product list with constructor
public ProductAdapter(Activity activity, List<Product> productList) {
// this.mCtx = mCtx;
create = activity;
this.productList = productList;
}
@Override
public ProductViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
//inflating and returning our view holder
LayoutInflater inflater = LayoutInflater.from(create);
View view = inflater.inflate(R.layout.layout_products, null);
return new ProductViewHolder(view);
}
@Override
public void onBindViewHolder(final ProductViewHolder holder, final int position) {
// //getting the product of the specified position
ArrayAdapter<String> spinnerArrayAdapter = new ArrayAdapter<String>(create, R.layout.item_spinner_layout,
Product.getSpinnerItemsList());
spinnerArrayAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
holder.spinner.setAdapter(spinnerArrayAdapter);
holder.spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> parent, View view, int mPosition, long id) {
mSpinnerSelectedItem.put(position, mPosition);
TextView mTextView = view.findViewById(R.id.mSpinnerText);
/* Toast.makeText(create, "Selected Item: " + mTextView.getText().toString(), Toast.LENGTH_LONG).show();
Log.e("***************", "Selected Item: " + mTextView.getText().toString());*/
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
}
});
//binding the data with the viewholder views
if (mSpinnerSelectedItem.containsKey(position)) {
holder.spinner.setSelection(mSpinnerSelectedItem.get(position));
}
holder.getView().setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(create);
// set title
alertDialogBuilder.setTitle("Delete Item");
// set dialog message
alertDialogBuilder
.setMessage("Are you sure you want to delete this item?")
.setCancelable(false)
.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
// if this button is clicked, close
// current activity
holder.checkBox.setChecked(false);
holder.spinner.setSelection(0);
productList.remove(position);
notifyItemRemoved(position);
Toast.makeText(create, "Item removed.", Toast.LENGTH_LONG).show();
}
})
.setNegativeButton("No", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
// if this button is clicked, just close
// the dialog box and do nothing
dialog.cancel();
}
});
// create alert dialog
AlertDialog alertDialog = alertDialogBuilder.create();
// show it
alertDialog.show();
}
});
}
@Override
public int getItemCount() {
return productList.size();
}
class ProductViewHolder extends RecyclerView.ViewHolder {
SearchableSpinner spinner;
EditText editText;
TextView textView5;
CheckBox checkBox;
LinearLayout linearLayout;
View rootView;
public ProductViewHolder(View itemView) {
super(itemView);
spinner = itemView.findViewById(R.id.spinner);
editText = itemView.findViewById(R.id.editText);
textView5 = itemView.findViewById(R.id.textView5);
checkBox = itemView.findViewById(R.id.checkBox);
rootView = itemView.findViewById(R.id.linearLayout);
checkBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
// makes the set disappear when checkbox is ticked.
if(isChecked){
checkBox.setChecked(false);
spinner.setSelection(0);
productList.remove(getAdapterPosition());
notifyItemRemoved(getAdapterPosition());
Toast.makeText(create, "Done!", Toast.LENGTH_LONG).show();
}
}
});
}
public View getView() {
return rootView;
}
}
}
对此：
arr(i) = N * ( 1 - ( 1 - 1 / N ) ^ arr(i - 1) );
我已经整理了所有内容，因此您可以更好地了解问题出在哪里。您已将括号移到错误的位置。
应该是：
comp_arr[i] = N * ( 1 - ( 1 - 1 / N ) ) ** comp_arr[i-1]
类似地，
comp_arr[i] = N * ( 1 - ( 1 - 1 / N ) ** comp_arr[i-1] )
与
不同ret = 1 - (1 - 1 / N) ^ exp;
应该是
probability = (1 - (1 - 1 / N)) ** final_exp