// Fhourstones 3.0 Board Logic
// Copyright 2000-2004 John Tromp
import java.io.*;
class Connect4 {
static long color[]; // black and white bitboard
static final int WIDTH = 7;
static final int HEIGHT = 6;
// bitmask corresponds to board as follows in 7x6 case:
// . . . . . . . TOP
// 5 12 19 26 33 40 47
// 4 11 18 25 32 39 46
// 3 10 17 24 31 38 45
// 2 9 16 23 30 37 44
// 1 8 15 22 29 36 43
// 0 7 14 21 28 35 42 BOTTOM
static final int H1 = HEIGHT+1;
static final int H2 = HEIGHT+2;
static final int SIZE = HEIGHT*WIDTH;
static final int SIZE1 = H1*WIDTH;
static final long ALL1 = (1L<<SIZE1)-1L; // assumes SIZE1 < 63
static final int COL1 = (1<<H1)-1;
static final long BOTTOM = ALL1 / COL1; // has bits i*H1 set
static final long TOP = BOTTOM << HEIGHT;
int moves[],nplies;
byte height[]; // holds bit index of lowest free square
public Connect4()
{
color = new long[2];
height = new byte[WIDTH];
moves = new int[SIZE];
reset();
}
void reset()
{
nplies = 0;
color[0] = color[1] = 0L;
for (int i=0; i<WIDTH; i++)
height[i] = (byte)(H1*i);
}
public long positioncode()
{
return 2*color[0] + color[1] + BOTTOM;
// color[0] + color[1] + BOTTOM forms bitmap of heights
// so that positioncode() is a complete board encoding
}
public String toString()
{
StringBuffer buf = new StringBuffer();
for (int i=0; i<nplies; i++)
buf.append(1+moves[i]);
buf.append("\n");
for (int w=0; w<WIDTH; w++)
buf.append(" "+(w+1));
buf.append("\n");
for (int h=HEIGHT-1; h>=0; h--) {
for (int w=h; w<SIZE1; w+=H1) {
long mask = 1L<<w;
buf.append((color[0]&mask)!= 0 ? " @" :
(color[1]&mask)!= 0 ? " 0" : " .");
}
buf.append("\n");
}
if (haswon(color[0]))
buf.append("@ won\n");
if (haswon(color[1]))
buf.append("O won\n");
return buf.toString();
}
// return whether columns col has room
final boolean isplayable(int col)
{
return islegal(color[nplies&1] | (1L << height[col]));
}
// return whether newboard lacks overflowing column
final boolean islegal(long newboard)
{
return (newboard & TOP) == 0;
}
// return whether newboard is legal and includes a win
final boolean islegalhaswon(long newboard)
{
return islegal(newboard) && haswon(newboard);
}
// return whether newboard includes a win
final boolean haswon(long newboard)
{
long y = newboard & (newboard>>HEIGHT);
if ((y & (y >> 2*HEIGHT)) != 0) // check diagonal \
return true;
y = newboard & (newboard>>H1);
if ((y & (y >> 2*H1)) != 0) // check horizontal -
return true;
y = newboard & (newboard>>H2); // check diagonal /
if ((y & (y >> 2*H2)) != 0)
return true;
y = newboard & (newboard>>1); // check vertical |
return (y & (y >> 2)) != 0;
}
void backmove()
{
int n;
n = moves[--nplies];
color[nplies&1] ^= 1L<<--height[n];
}
void makemove(int n)
{
color[nplies&1] ^= 1L<<height[n]++;
moves[nplies++] = n;
}
public static void main(String argv[])
{
Connect4 c4;
String line;
int col=0, i, result;
long nodes, msecs;
c4 = new Connect4();
c4.reset();
BufferedReader dis = new BufferedReader(new InputStreamReader(System.in));
for (;;) {
System.out.println("position " + c4.positioncode() + " after moves " + c4 + "enter move(s):");
try {
line = dis.readLine();
} catch (IOException e) {
System.out.println(e);
System.exit(0);
return;
}
if (line == null)
break;
for (i=0; i < line.length(); i++) {
col = line.charAt(i) - '1';
if (col >= 0 && col < WIDTH && c4.isplayable(col))
c4.makemove(col);
}
}
}
}
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