Google Code Jam - WordPath

Google Code Jam - WordPath

- Implementation

public   class  WordPath {    
     public   int  countPaths(String[] grid, String find) {
         int  length  =  grid.length  +   2 ;      
        
         // convert "grid" from String to char matrix
         char [][] charGrid  =   new   char [length][length];
         for  ( int  i  =   0 ; i  <  length; i ++ ) {
             for  ( int  j  =   0 ; j  <  length; j ++ ) {
                 if  (i  ==   0   ||  i  ==  length  -   1   ||  j  ==   0   ||  j  ==  length  -   1 )
                    charGrid[i][j]  =   ' 0 ' ;
                 else
                    charGrid[i][j]  =  grid[i  -   1 ].charAt(j  -   1 );
            }
        }
        
         // convert "find" from String to char array
         char [] charFind  =   new   char [find.length()];
         for  ( int  k  =   0 ; k  <  find.length(); k ++ )
            charFind[k]  =  find.charAt(k);

         // use three dimensions "degree" to hold the in-degree of the vertex of graph
         int [][][] degree  =   new   int [length][length][find.length()];        

         //  k=0
         for  ( int  i  =   0 ; i  <  length; i ++ )
             for  ( int  j  =   0 ; j  <  length; j ++ ) {
                degree[i][j][ 0 ]  =  ((charGrid[i][j]  ==  charFind[ 0 ])  ?   1  :  0 );
            }
        
         //  fill the degree 
         for  ( int  k  =   1 ; k  <  find.length(); k ++ ) {
             for  ( int  i  =   0 ; i  <  length; i ++ )
                 for  ( int  j  =   0 ; j  <  length; j ++ ) {
                     if  (charGrid[i][j]  !=  charFind[k])
                        degree[i][j][k]  =   0 ;
                     else  {
                        degree[i][j][k]  =  degree[i  -   1 ][j  -   1 ][k  -   1 ]  +  degree[i  -   1 ][j][k  -   1 ]
                                 +  degree[i  -   1 ][j  +   1 ][k  -   1 ]  +  degree[i  +   1 ][j  -   1 ][k  -   1 ]
                                 +  degree[i  +   1 ][j][k  -   1 ]  +  degree[i  +   1 ][j  +   1 ][k  -   1 ]
                                 +  degree[i][j  -   1 ][k  -   1 ]  +  degree[i][j  +   1 ][k  -   1 ];

                    }

                }
        }
        
         // calculate the sum
         int  sum  =   0 ;
         for  ( int  i  =   0 ; i  <  length; i ++ )
             for  ( int  j  =   0 ; j  <  length; j ++ ) {
                sum  +=  degree[i][j][find.length()  -   1 ];
                 if  (sum  >   1000000000 ) {
                     return   - 1 ;
                }
            }
         return  sum;
    }
}

- TestCase

public   class  WordPathTest  extends  TestCase {
     public   void  testCountPaths() {
        WordPath wordPath  =   new  WordPath();
        assertEquals( 2 , wordPath.countPaths( new  String[] {  " ABC " ,  " FED " ,  " GAI "  },  " ABCDEA " ));
        assertEquals( 0 , wordPath.countPaths( new  String[] {  " ABC " ,  " DEF " ,  " GHI "  },  " ABCD " ));
        assertEquals( 108 , wordPath.countPaths( new  String[] {  " AA " ,  " AA "  },  " AAAA " ));
        assertEquals( 56448 , wordPath.countPaths( new  String[] {  " ABABA " ,  " BABAB " ,  " ABABA " ,  " BABAB " ,  " ABABA "  },
                 " ABABABBA " ));
        assertEquals( - 1 , wordPath.countPaths( new  String[] {  " AAAAA " ,  " AAAAA " ,  " AAAAA " ,  " AAAAA " ,  " AAAAA "  },
                 " AAAAAAAAAAA " ));
        assertEquals( 0 , wordPath.countPaths( new  String[] {  " AB " ,  " CD "  },  " AA " ));
    }
}

This testcase finished after 0.015 seconds on my pc.

http://forum.javaeye.com/viewtopic.php?p=106316#106316