How can I print out all possible letter combinations a given phone number can represent?

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逝去的感伤 2020-12-22 18:01

I just tried for my first programming interview and one of the questions was to write a program that given a 7 digit telephone number, could print all possible combinations

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無奈伤痛 (楼主)

2020-12-22 18:37

#include 
#include 
#include 

map< int, string> keyMap;

void MakeCombinations( string first, string joinThis , vector& eachResult )
{
    if( !first.size() )
        return;

    int length = joinThis.length();
    vector result;

    while( length )
    {
        string each;
        char firstCharacter = first.at(0);
        each =  firstCharacter;
        each += joinThis[length -1];
        length--;

        result.push_back(each);     
    }

    first = first.substr(1);

    vector::iterator begin = result.begin();    
    vector::iterator end = result.end();
    while( begin != end)
    {
        eachResult.push_back( *begin);
        begin++;
    }

    return MakeCombinations( first, joinThis, eachResult);
}


void ProduceCombinations( int inNumber, vector& result)
{
    vector inputUnits;

    int number = inNumber;
    while( number )
    {
        int lastdigit ;

        lastdigit = number % 10;
        number = number/10;
        inputUnits.push_back( keyMap[lastdigit]);
    }

    if( inputUnits.size() == 2)
    {
        MakeCombinations(inputUnits[0], inputUnits[1], result);
    }
    else if ( inputUnits.size() > 2 )
    {
        MakeCombinations( inputUnits[0] , inputUnits[1], result);

        vector::iterator begin = inputUnits.begin();    
        vector::iterator end = inputUnits.end();

        begin += 2;
        while(  begin != end )
        {
            vector intermediate = result;
            vector::iterator ibegin = intermediate.begin(); 
            vector::iterator iend = intermediate.end(); 

            while( ibegin != iend)
            {
                MakeCombinations( *ibegin , *begin, result);
                //resultbegin =  
                ibegin++; 
            }
            begin++;            
        }
    }
    else
    {

    }

    return;
}

int _tmain(int argc, _TCHAR* argv[])
{
    keyMap[1] = "";
    keyMap[2] = "abc";
    keyMap[3] = "def";
    keyMap[4] = "ghi";
    keyMap[5] = "jkl";
    keyMap[6] = "mno";
    keyMap[7] = "pqrs";
    keyMap[8] = "tuv";
    keyMap[9] = "wxyz";
    keyMap[0] = "";

    string  inputStr;
    getline(cin, inputStr);

    int number = 0;

    int length = inputStr.length();

    int tens = 1;
    while( length )
    {
        number += tens*(inputStr[length -1] - '0');
        length--;
        tens *= 10;
    }

    vector r;
    ProduceCombinations(number, r);

    cout << "[" ;

    vector::iterator begin = r.begin(); 
    vector::iterator end = r.end();

    while ( begin != end)
    {
        cout << *begin << "," ;
        begin++;
    }

    cout << "]" ;

    return 0;
}

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