Permutations of letters and numbers in a phone number - c++

Question

For my computer science class, we need to write a program (in C++) that takes an input of characters and outputs the possible permutations of it according to the dial pad on a phone, leaving non-digit characters in place.
For example, inputing 2 outputs 2, A, B, C. Inputing 23 outputs 23, A3, B3, C3, 2D, 2E, 2F, AD, AE, AF, BD, BE, BF, etc...
The application provided for this program is finding permutations of "vanity" phone numbers for a given phone number.
Currently, the program I have written doesn't even compile, and I'm afraid the algorithm I'm using is incorrect:
#include <iostream>
#include <multimap.h>
#include <vector>
using namespace std;
// Prototypes
void initLetterMap(multimap<char,char> &lmap);
void showPermutations(const vector<string> &perms);
vector<string> getPermutations(const string &phoneNumber,const multimap<char,char> &lmap);
vector<char> getLetters(char digit, const multimap<char,char> &lmap);
// Declarations
void initLetterMap(multimap<char,char> &lmap) {
lmap.insert(pair<char,char>('1','1'));
lmap.insert(pair<char,char>('2','2'));
lmap.insert(pair<char,char>('2','A'));
lmap.insert(pair<char,char>('2','B'));
lmap.insert(pair<char,char>('2','C'));
lmap.insert(pair<char,char>('3','3'));
lmap.insert(pair<char,char>('3','D'));
lmap.insert(pair<char,char>('3','E'));
lmap.insert(pair<char,char>('3','F'));
// ...
}
vector<char> getLetters(char digit, const multimap<char,char> &lmap) {
multimap<char,char>::iterator it;
pair<multimap<char,char>::iterator,multimap<char,char>::iterator> range;
vector<char> result;
if (isdigit(digit)) {
range = lmap.equal_range(digit);
for (it=range.first;it!=range.second;++it) {
result.push_back((*it).second);
}
} else {
result.insert(result.end(),digit);
}
return result;
}
void showPermutations(vector<string> &perms) {
vector<string>::iterator it;
for (it = perms.begin(); it != perms.end(); it++) {
cout << *it << endl;
}
}
vector<string> getPermutations(const string &phoneNumber,const multimap<char,char> &lmap) {
vector<string> results;
string number = phoneNumber;
vector<char>::iterator vcit;
vector<char> letters;
unsigned int i;
for (i=0;i<phoneNumber.length();i++) {
letters = getLetters(number[i],lmap);
for (vcit=letters.begin();vcit!=letters.end();vcit++) {
number[i] = *vcit;
results.push_back(number);
}
}
return results;
}
int main() {
multimap<char,char> lmap;
initLetterMap(lmap);
string input;
cout << "Enter a phone number to get all possible vanity numbers" << endl;
cout << "> "; getline(cin,input);
showPermutations(getPermutations(input,lmap));
return 0;
}
I get a whole slew of build issues when I try to build this, and am not sure how to resolve most of them:
In file included from /usr/include/c++/4.0.0/backward/multimap.h:59,
from phone02.cpp:18:
/usr/include/c++/4.0.0/backward/backward_warning.h:32:2: warning: #warning This file includes at least one deprecated or antiquated header. Please consider using one of the 32 headers found in section 17.4.1.2 of the C++ standard. Examples include substituting the <X> header for the <X.h> header for C++ includes, or <iostream> instead of the deprecated header <iostream.h>. To disable this warning use -Wno-deprecated.
/usr/include/c++/4.0.0/bits/stl_pair.h: In constructor 'std::pair<_T1, _T2>::pair(const std::pair<_U1, _U2>&) [with _U1 = std::_Rb_tree_const_iterator<std::pair<const char, char> >, _U2 = std::_Rb_tree_const_iterator<std::pair<const char, char> >, _T1 = std::_Rb_tree_iterator<std::pair<const char, char> >, _T2 = std::_Rb_tree_iterator<std::pair<const char, char> >]':
phone02.cpp:75: instantiated from here
/usr/include/c++/4.0.0/bits/stl_pair.h:90: error: no matching function for call to 'std::_Rb_tree_iterator<std::pair<const char, char> >::_Rb_tree_iterator(const std::_Rb_tree_const_iterator<std::pair<const char, char> >&)'
/usr/include/c++/4.0.0/bits/stl_tree.h:167: note: candidates are: std::_Rb_tree_iterator<_Tp>::_Rb_tree_iterator(std::_Rb_tree_node<_Tp>*) [with _Tp = std::pair<const char, char>]
/usr/include/c++/4.0.0/bits/stl_tree.h:164: note: std::_Rb_tree_iterator<_Tp>::_Rb_tree_iterator() [with _Tp = std::pair<const char, char>]
/usr/include/c++/4.0.0/bits/stl_tree.h:152: note: std::_Rb_tree_iterator<std::pair<const char, char> >::_Rb_tree_iterator(const std::_Rb_tree_iterator<std::pair<const char, char> >&)
/usr/include/c++/4.0.0/bits/stl_pair.h:90: error: no matching function for call to 'std::_Rb_tree_iterator<std::pair<const char, char> >::_Rb_tree_iterator(const std::_Rb_tree_const_iterator<std::pair<const char, char> >&)'
/usr/include/c++/4.0.0/bits/stl_tree.h:167: note: candidates are: std::_Rb_tree_iterator<_Tp>::_Rb_tree_iterator(std::_Rb_tree_node<_Tp>*) [with _Tp = std::pair<const char, char>]
/usr/include/c++/4.0.0/bits/stl_tree.h:164: note: std::_Rb_tree_iterator<_Tp>::_Rb_tree_iterator() [with _Tp = std::pair<const char, char>]
/usr/include/c++/4.0.0/bits/stl_tree.h:152: note: std::_Rb_tree_iterator<std::pair<const char, char> >::_Rb_tree_iterator(const std::_Rb_tree_iterator<std::pair<const char, char> >&)
make: *** [phone02.o] Error 1
The line numbers are a bit off, but the important ones that I can see are the two about no matching function for call to 'std::_Rb_tree_iterator<std::pair<const char, char> >::_Rb_tree_iterator(const std::_Rb_tree_const_iterator<std::pair<const char, char> >&)'
Besides the errors, I also believe I am heading in the wrong direction with my algorithm.
So I have 2 questions here:
Why am I getting these build errors, and how do I fix them?
How would you suggest going about solving this problem? Am I on the right track or no?
For question #2, I would prefer to not get solutions, just advice or pointers in the right direction.
Thanks!
PS: I am building this on Mac OS X 10.5.8 with gcc, using QtCreator 1.2.1
UPDATE:
I have successfully compiled a solution program. I will post the source code to those who are curious.
#include <iostream>
#include <map>
#include <vector>
#include <string>
using namespace std;
void initLetterMap(map<char,string> &lmap);
vector<string> getMapped(const string &phoneNumber, map<char,string> &lmap);
vector<string> getPermutations(vector<string> number);
unsigned long int countPermutations(vector<string> number);
void initLetterMap(map<char,string> &lmap) {
lmap['0'] = "0";
lmap['1'] = "1";
lmap['2'] = "2ABC";
lmap['3'] = "3DEF";
lmap['4'] = "4GHI";
lmap['5'] = "5JKL";
lmap['6'] = "6MNO";
lmap['7'] = "7PQRS";
lmap['8'] = "8TUV";
lmap['9'] = "9WXYZ";
}
unsigned long int countPermutations(vector<string> number) {
long int fold = 1;
int vals = 0;
vector<string>::iterator it;
for (it=number.begin();it!=number.end();it++) {
vals = (*it).length();
fold *= vals;
}
return fold;
}
vector<string> getMapped(const string &phoneNumber, map<char,string> &lmap) {
unsigned int i;
vector<string> out;
char digit;
string temp;
for (i=0;i<phoneNumber.length();i++) {
digit = phoneNumber.at(i);
if (isdigit(digit)) {
out.push_back(lmap[digit]);
} else {
temp = string(1,digit);
out.push_back(temp);
}
}
return out;
}
vector<string> getPermutations(vector<string> number) {
vector<string> results;
unsigned long int i,j,k;
unsigned long int perms = countPermutations(number);
vector<string>::reverse_iterator numit;
string temp,temp2;
vector<int> state = vector<int>(number.size(), 0);
vector<int>::reverse_iterator stateit;
for (i=0;i<perms;i++) {
j=i;
temp = "";
for (stateit=state.rbegin(), numit=number.rbegin();stateit!=state.rend();stateit++, numit++) {
*stateit = j % (*numit).length();
j /= (*numit).length();
temp.insert(temp.begin(),(*numit)[*stateit]);
}
results.push_back(temp);
}
return results;
}
int main() {
map<char,string> lettermap;
initLetterMap(lettermap);
string input;
cout << "> "; getline(cin,input);
vector<string> perms = getPermutations(getMapped(input,lettermap));
vector<string>::iterator it;
for (it=perms.begin();it!=perms.end();it++) {
cout << *it << endl;
}
}
The code is probably more complicated than it has to be, but my goal was to just get it to work. It seems to run fairly quickly for 10 digit phone numbers, so I guess it's not too bad.
Thanks to Jacob and ShreevatsaR for getting me pointed in the right direction!

Answer 1

How about the following:
#include <cstddef>
#include <iostream>
#include <iterator>
#include <string>
#include <algorithm>
template <typename Iterator>
bool next_combination(const Iterator first, Iterator k, const Iterator last);
int main()
{
std::string phone_number = "23";
std::string number[] = {
"0", "1", "2abc", "3def", "4ghi",
"5jkl","6mno", "7pqrs", "8tuv","9wxyz"
};
std::string tmp_set;
std::string set;
for(std::size_t i = 0; i < phone_number.size(); ++i)
{
tmp_set += number[static_cast<std::size_t>(phone_number[i] - '0')];
}
std::sort(tmp_set.begin(),tmp_set.end());
std::unique_copy(tmp_set.begin(),
tmp_set.end(),
std::back_inserter(set));
std::string current_set;
current_set.reserve(phone_number.size());
do
{
std::copy(set.begin(),
set.begin() + phone_number.size(),
std::back_inserter(current_set));
do
{
std::cout << current_set << std::endl;
}
while (std::next_permutation(current_set.begin(),current_set.end()));
current_set.clear();
}
while(next_combination(set.begin(),
set.begin() + phone_number.size(),
set.end()));
return 0;
}
template <typename Iterator>
inline bool next_combination(const Iterator first, Iterator k, const Iterator last)
{
/* Credits: Thomas Draper */
if ((first == last) || (first == k) || (last == k))
return false;
Iterator itr1 = first;
Iterator itr2 = last;
++itr1;
if (last == itr1)
return false;
itr1 = last;
--itr1;
itr1 = k;
--itr2;
while (first != itr1)
{
if (*--itr1 < *itr2)
{
Iterator j = k;
while (!(*itr1 < *j)) ++j;
std::iter_swap(itr1,j);
++itr1;
++j;
itr2 = k;
std::rotate(itr1,j,last);
while (last != j)
{
++j;
++itr2;
}
std::rotate(k,itr2,last);
return true;
}
}
std::rotate(first,k,last);
return false;
}

Answer 2

Well if you don't want a solution, I would implement it like this:
Use a vector V with each element drawn from a string. E.g. if it's 23, then your vector V, would have two vectors each containing 2ABC and 3DEF.
Iterate each digit like a counter through the associated string. Move right-to-left and when each digit overflows increment the one to the left, and reset, etc.
Display the counter at every iteration to obtain your "number".

Answer 3

Hint to compile errors:
there is no file called <multimap.h> in STL. it should be <map>
The problem is with getLetters function. multimap lmap has been passed by const reference. Hence, equal_range API on lmap would return pair of const_iterator not just iterator.

Answer 4

Below code demonstrate how to do it in simple steps(Recursively):
1.) Create vector of strings, and push strings which represents "possible characters resulting from that keypress" (0-key to 9-key).
2.) Since each keypress will serve to add ONLY one char to the resultant string, append only one character at a time and call the function recursively for the next keypress. Do it for each possible char at that keypress.
Demo:
void getCombination(vector<string> &combinations, string current, const string &A, int idx, const vector<string> &keyset){
if(idx >= A.size()) {
combinations.push_back(current);
return;
}
int key = (A[idx] - '0');
int len = keyset[key].length();
for( int i = 0; i < len; i++ ){
current.push_back(keyset[key][i]); //pick at once one char corresp. to that keypress
getCombination(combinations, current, A, idx+1, keyset);
current.pop_back();
}
}
vector<string> letterCombinations(string A) {
vector<string> combinations;
vector<string> keyset{"0", "1", "2abc", "3def", "4ghi", "5jkl", "6mno", "7pqrs", "8tuv", "9wxyz"};
getCombination(combinations, std::string({}), A, 0, keyset);
return combinations;
}
int main() {
vector<string> combinations = letterCombinations("23");
for(string word : combinations){
cout << word << ", ";
}
return 0;
}
Gives Output :
23, 2d, 2e, 2f, a3, ad, ae, af, b3, bd, be, bf, c3, cd, ce, cf,