+0

# To: Max Wong

+1
94
1

Hello Max! Can you please take a look at this question and see if you can arrive at the same answer (2,111) using combination and permutations?   https://web2.0calc.com/questions/set-theory

Thanks alot.

Jun 14, 2020

#1
+8341
0

Sorry, I am bad at combinatorics, but same as that Guest who answered your question, I wrote a program to verify Guest's answer, and it's correct. Here's my source code in C++:

#include
using namespace std;
string s = "122333444455555";
int main(){
set se;
do{
se.insert(s.substr(0, 5));
} while (next_permutation(s.begin(), s.end()));
cout << se.size() << endl;
}

You can run it yourself on a suitable IDE(Integrated Development Environment) for C++, or just find one to run on by searching "online C++ IDE" on Google. You will see that the result is 2111.

Edit: I don't know why a part of my code keep disappearing. But the first line is $$\#\text{include}<\text{bits/stdc++.h}>$$ and the fifth line is $$\text{set}<\text{string}> \text{se};$$.

Jun 14, 2020
edited by MaxWong  Jun 14, 2020
edited by MaxWong  Jun 14, 2020
edited by MaxWong  Jun 14, 2020
edited by MaxWong  Jun 14, 2020