Question

in C programming language, write and test a function that writes and returns through an output parameter the longest common suffix of two words. (e.g. The longest common suffix of "destination" and "procrastination" is "stination", of "globally" and "internally" is "ally, and of "glove" and "dove" is the empty string)

Answer 1

#include <string>
#include <algorithm>
#include <iostream>
#include <set>
#include <vector>
using namespace std;
void findSubstrings ( const string & word , set< string> & substrings ) {
   int l = word.length( ) ;
   for ( int start = 0 ; start < l ; start++ ) {
      for ( int length = 1 ; length < l - start + 1 ; length++ ) {
   substrings.insert ( word.substr( start , length ) ) ;
      }
   }
}
string longestCommonSuffix ( const string & first , const string & second ) {
    set< string> firstSubstrings , secondSubstrings ;
   findSubstrings ( first , firstSubstrings ) ;
   findSubstrings ( second , secondSubstrings ) ;
    set< string> common ;
    set_intersection ( firstSubstrings.begin( ) , firstSubstrings.end( ) ,
   secondSubstrings.begin( ) , secondSubstrings.end( ) ,
      inserter ( common , common.begin( ) ) ) ;
    vector< string> commonSubs ( common.begin( ) , common.end( ) ) ;
    sort ( commonSubs.begin( ) , commonSubs.end( ) , []( const string &s1 ,
        const string &s2 ) { return s1.length( ) > s2.length( ) ; } ) ;
   return *(commonSubs.begin( ) ) ;
}

int main( ) {
    string s1 ("procrastination" ) ;
    string s2 ( "stination" ) ;
    cout << "The longest common substring of " << s1 << " and " << s2 << " is:\n" ;
    cout << longestCommonSuffix ( s1 , s2 ) << " !\n" ;
   return 0 ;
}