generate_all_possible_password.txt

/*
 Find all the possible passwords, given the length of the password and that it is a well ordered number (159 is well-ordered as 1<5<9)
*/

#include <iostream>
using namespace std;

/*outputPW() print all the possible combination of password, given the length of the password.*/
void outputPW(int arr[], int len, int index){
    if (index==len){
        /*decide if the password is well-ordered, that is strictly ascending. If so, print it; otherwise discare it.*/
        int flag=1;
        for (int i=0; i<len-1; ++i){
            if (arr[i]>=arr[i+1]){
                flag=0;
                break;
            }
        }
        if (flag==1){
            for (int i=0; i<len; ++i)
                cout<<arr[i];
            cout<<endl;
            return;
        }
        else return;
    }
    else{
        for (int i=0; i<=9; ++i){
            arr[index]=i;
            outputPW(arr,len,index+1);
        }
    }
}

int main(){
    cout<<"Input the length of the password:"<<endl;
    int length;
    cin>>length;
    if (length<0){
        cout<<"The length cannot be negative."<<endl;
        return -1;
    }
    int *arr = new int[length];
    outputPW(arr,length, 0);
    delete arr;
    return 0;
}

REMARK
1. First self written recursive code. Similar to the other code "keypad" in the repository "Hello-World".
2. COMMON ERROR, wrote "if (flag==0)" into "if (flag=0)".