CODEWITHSUNDEEP
c++
satyajeet jha
satyajeet jha

Reputation: 163

next_permutation in c++ on strings

My code accepts a string and tries to check if there exists a permutation of the input string or not.If there exists one such string ,print it else print "no answer ".But my code doesn't compile and shows error. error is ::no matching function for call to 'next_permutation(std::string&)'| what is the correct method to accomplish this task ?

#include <bits/stdc++.h>
using namespace std;
int main(){
    int t;
    cin>>t;
    while(t--){
        string s;
        cin>>s;
        string ans=next_permutation(s);// do permutation and store it in string ans
        if(ans==s)// if there is no permutation possible original and ans will be same
            cout<<"no answer "<<endl;
        else
            cout<<ans<<endl;// else print ans
    }
}

Upvotes: 1

Views: 8345

Answers (4)

arshovon
arshovon

Reputation: 13651

This code also solves the problem:

#include <bits/stdc++.h>
using namespace std;
int main(){
    int t;
    cin>>t;
    while(t--){
        string s;
        cin>>s;
        string original_s=s; // store the input string in a variable as original_s
        next_permutation(s.begin(),s.end());// do permutation and s will be changed if permutation occurs
        if(s==original_s)// if there is no permutation possible original and s will be same
            cout<<"no answer "<<endl;
        else
            cout<<s<<endl;// else print ans
    }
}

Upvotes: 0

satyajeet jha
satyajeet jha

Reputation: 163

this is the correct way to do this 

       // thanks to rajeev's code
       #include <bits/stdc++.h>
         using namespace std;
         int main(){
         int t;
         cin>>t;
         while(t--){
           string s;
           cin>>s;
           bool ans=next_permutation(s.begin(),s.end());
           if(!ans)
           cout<<"no answer "<<endl;
           else
           cout<<s<<endl;

            }
         }

Upvotes: 0

Rajeev Singh
Rajeev Singh

Reputation: 3332

Here are the prototypes of the function next_permutation and your calling statement string ans=next_permutation(s); doesn't matches any of them.

template <class BidirectionalIterator>
  bool next_permutation (BidirectionalIterator first,
                         BidirectionalIterator last);

template <class BidirectionalIterator, class Compare>
  bool next_permutation (BidirectionalIterator first,
                         BidirectionalIterator last, Compare comp);

Change your code like this to check weather a permutation exits or not

if(next_permutation(s.begin(),s.end()))
    cout<<s<<endl;
else
    cout<<"no answer "<<endl;

And If you want to print all the permutations of s then do this

while(next_permutation(s.begin(),s.end()))
{
    cout<<s<<endl;
}

This is the way to do it,although you may have to change the logic to accomplish the task

Upvotes: 2

eerorika
eerorika

Reputation: 238311

The compilation error is quite clear:

no matching function for call to 'next_permutation(std::string&)'|

The compiler tells you that there exists no function next_permutation(std::string&). If you take a look at the documentation, you'll find that is indeed the case. There are two overloads:

template< class BidirIt >
bool next_permutation( BidirIt first, BidirIt last );

template< class BidirIt, class Compare >
bool next_permutation( BidirIt first, BidirIt last, Compare comp );

Neither of them matches your call.

Use std::string::begin and std::string::end to get iterators to the range of characters inside the string.

Upvotes: 0

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