public boolean ld_play( int i, int j, int val ){
        int nval = -val;
        int i1 = i+1;
        int j1=j-1;
        while( i1<values.length && j1>=0 && values[i1][j1] == nval ){
            i1++;
            j1--;
        }
        if( i1<values.length && j1>=0 && i+1 < i1 && values[i1][j1] == val ){
            // Valid play
            for( int k=i+1; k<i1; k++ ){
                j--;
                values[k][j] = val;
            }
            return true;
        }
        return false;        
    }