136 lines
4.8 KiB
D
136 lines
4.8 KiB
D
// Created by Lionello Lunesu and placed in the public domain.
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// This file has been modified from its original version.
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// It has been formatted to fit your screen.
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module phoneno; // optional
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import std.stdio; // writefln
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import std.ctype; // isdigit
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import std.stream; // BufferedFile
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// Just for readability (imagine char[][][char[]])
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alias char[] string;
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alias string[] stringarray;
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/// Strips non-digit characters from the string (COW)
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string stripNonDigit( in string line )
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{
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string ret;
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foreach(uint i, c; line) {
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// Error: std.ctype.isdigit at C:\dmd\src\phobos\std\ctype.d(37)
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// conflicts with std.stream.isdigit at C:\dmd\src\phobos\std\stream.d(2924)
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if (!std.ctype.isdigit(c)) {
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if (!ret)
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ret = line[0..i];
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}
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else if (ret)
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ret ~= c;
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}
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return ret?ret:line;
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}
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unittest {
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assert( stripNonDigit("asdf") == "" );
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assert( stripNonDigit("\'13-=2 4kop") == "1324" );
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}
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/// Converts a word into a number, ignoring all non alpha characters
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string wordToNum( in string word )
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{
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// translation table for the task at hand
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const char[256] TRANSLATE =
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" " // 0
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" 0123456789 " // 32
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" 57630499617851881234762239 " // 64
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" 57630499617851881234762239 "
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" "
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" "
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" "
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" ";
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string ret;
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foreach(c; cast(ubyte[])word)
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if (TRANSLATE[c] != ' ')
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ret ~= TRANSLATE[c];
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return ret;
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}
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unittest {
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// Test wordToNum using the table from the task description.
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assert( "01112223334455666777888999" ==
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wordToNum("E | J N Q | R W X | D S Y | F T | A M | C I V | B K U | L O P | G H Z"));
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assert( "01112223334455666777888999" ==
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wordToNum("e | j n q | r w x | d s y | f t | a m | c i v | b k u | l o p | g h z"));
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assert( "0123456789" ==
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wordToNum("0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9"));
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}
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void main( string[] args )
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{
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// This associative array maps a number to an array of words.
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stringarray[string] num2words;
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foreach(string word; new BufferedFile("dictionary.txt" ) )
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num2words[ wordToNum(word) ] ~= word.dup; // must dup
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/// Finds all alternatives for the given number
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/// (should have been stripped from non-digit characters)
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stringarray _FindWords( string numbers, bool digitok )
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in {
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assert(numbers.length > 0);
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}
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out(result) {
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foreach (a; result)
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assert( wordToNum(a) == numbers );
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}
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body {
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stringarray ret;
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bool foundword = false;
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for (uint t=1; t<=numbers.length; ++t) {
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auto alternatives = numbers[0..t] in num2words;
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if (!alternatives)
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continue;
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foundword = true;
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if (numbers.length > t) {
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// Combine all current alternatives with all alternatives
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// of the rest (next piece can start with a digit)
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foreach (a2; _FindWords( numbers[t..$], true ) )
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foreach(a1; *alternatives)
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ret ~= a1 ~ " " ~ a2;
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}
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else
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ret ~= *alternatives; // append these alternatives
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}
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// Try to keep 1 digit, only if we're allowed and no other
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// alternatives were found
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// Testing "ret.length" makes more sense than testing "foundword",
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// but the other implementations seem to do just this.
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if (digitok && !foundword) { //ret.length == 0
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if(numbers.length > 1) {
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// Combine 1 digit with all altenatives from the rest
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// (next piece can not start with a digit)
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foreach (a; _FindWords( numbers[1..$], false ) )
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ret ~= numbers[0..1] ~ " " ~ a;
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}
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else
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ret ~= numbers[0..1]; // just append this digit
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}
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return ret;
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}
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/// (This function was inlined in the original program)
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/// Finds all alternatives for the given phone number
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/// Returns: array of strings
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stringarray FindWords( string phone_number )
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{
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if (!phone_number.length)
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return null;
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// Strip the non-digit characters from the phone number, and
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// pass it to the recursive function (leading digit is allowed)
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return _FindWords( stripNonDigit(phone_number), true );
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}
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// Read the phone numbers
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foreach(string phone; new BufferedFile("input.txt" ) )
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foreach(alternative; FindWords( phone ) )
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writefln(phone, ": ", alternative );
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}
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