What is an appropriate data structure?

This is a discussion on What is an appropriate data structure? within the C Programming forums, part of the General Programming Boards category; Hi, I am working on a program that accepts a string of 7 letters and then tries to find every ...

  1. #1
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    Question What is an appropriate data structure?

    Hi,

    I am working on a program that accepts a string of 7 letters and then tries to find every word in a dictionary that contains those 7 letters.

    Basically it is an anagram program that finds valid scrabble words with given letters.

    Anyway, my dictionary file is a word list of over 200,000 words stored in a text file. My queston is, should i find all possible letter combinations of my 7 letters then compare each combination against each word in the list then return all matches?

    I'm not to concerned with the algorithm at present as it will evolve as i go, but i am trying to figure out the best way to store the word list.

    Should i just keep them in a file or should i try load them into an array or some other kind of structure? I did try loading them all into a sql database but people have told me that sql is quite inefficient for what i am trying to do.

    Any advice would be great.

    Thanks

  2. #2
    Gawking at stupidity
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    Anyway, my dictionary file is a word list of over 200,000 words stored in a text file. My queston is, should i find all possible letter combinations of my 7 letters then compare each combination against each word in the list then return all matches?
    That's a whole lot of CPU cycles. To make things more efficient I would probably use a hash table.
    If you understand what you're doing, you're not learning anything.

  3. #3
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    There is a much faster way. Here's an example.

    Word list:
    Code:
    alloc
    free
    locale
    main
    program
    Scrabble letters
    Code:
    locamle
    What do you do? First, sort and enumerate the letters of each word in the word list, and your letter rack itself:

    Code:
    program
    1 'a'
    0 'b'
    0 'c'
    ...
    1 'g'
    ...
    1 'm'
    0 'n'
    1 'o'
    1 'p'
    0 'q'
    2 'r'
    ...
    Then you check if each word can be formed using the given letters in the rack. Figure that out yourself.
    Code:
    #include <stdio.h>
    
    void J(char*a){int f,i=0,c='1';for(;a[i]!='0';++i)if(i==81){
    puts(a);return;}for(;c<='9';++c){for(f=0;f<9;++f)if(a[i-i%27+i%9
    /3*3+f/3*9+f%3]==c||a[i%9+f*9]==c||a[i-i%9+f]==c)goto e;a[i]=c;J(a);a[i]
    ='0';e:;}}int main(int c,char**v){int t=0;if(c>1){for(;v[1][
    t];++t);if(t==81){J(v[1]);return 0;}}puts("sudoku [0-9]{81}");return 1;}

  4. #4
    ATH0 quzah's Avatar
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    Since programmers learn best by example, here's one for you...
    Code:
    #include<stdio.h>
    int main( void ) { printf("Programmers learn best by example.\n"); return 0; }
    You also don't need a ; at the end of your main function...

    (Note for posterity: This refers to the above poster's sig.)

    Quzah.
    Hope is the first step on the road to disappointment.

  5. #5
    Registered User
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    Daggnabbit, that hurt. I'm scarred for life
    Code:
    #include <stdio.h>
    
    void J(char*a){int f,i=0,c='1';for(;a[i]!='0';++i)if(i==81){
    puts(a);return;}for(;c<='9';++c){for(f=0;f<9;++f)if(a[i-i%27+i%9
    /3*3+f/3*9+f%3]==c||a[i%9+f*9]==c||a[i-i%9+f]==c)goto e;a[i]=c;J(a);a[i]
    ='0';e:;}}int main(int c,char**v){int t=0;if(c>1){for(;v[1][
    t];++t);if(t==81){J(v[1]);return 0;}}puts("sudoku [0-9]{81}");return 1;}

  6. #6
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    You can read the text file word by word, transform it as stated in my post above, check if it can be formed using the tiles, keep/discard and read the next one in. That way, you won't be using much RAM at all. That is, if memory is an issue. If it isn't, I have ways to speed things up
    Last edited by jafet; 07-01-2006 at 07:52 AM.
    Code:
    #include <stdio.h>
    
    void J(char*a){int f,i=0,c='1';for(;a[i]!='0';++i)if(i==81){
    puts(a);return;}for(;c<='9';++c){for(f=0;f<9;++f)if(a[i-i%27+i%9
    /3*3+f/3*9+f%3]==c||a[i%9+f*9]==c||a[i-i%9+f]==c)goto e;a[i]=c;J(a);a[i]
    ='0';e:;}}int main(int c,char**v){int t=0;if(c>1){for(;v[1][
    t];++t);if(t==81){J(v[1]);return 0;}}puts("sudoku [0-9]{81}");return 1;}

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