Reformatted Tiny 2048.c

gistfile1.txt

M[16],X=16,W,k;

main(){
T(system("stty cbreak"));
puts(W&1?"WIN":"LOSE");
}

K[]={2,3,1};

s(f,d,i,j,l,P){
for(i=4;i--;)
	for(j=k=l=0;k<4;)
		j<4?P=M[w(d,i,j++)],W|=P>>11,l*P&&(f?M[w(d,i,k)]=l<<(l==P):0,k++),l=l?P?l-P?P:0:l:P:(f?M[w(d,i,k)]=l:0,++k,W|=2*!l,l=0);
}

w(d,i,j){
return d?w(d-1,j,3-i):4*i+j;
}

T(i){
for(i=X+rand()%X;M[i%X]*i;i--);
i?M[i%X]=2<<rand()%2:0;
for(W=i=0;i<4;)s(0,i++);
for(i=X,puts("\e[2J\e[H");i--;i%4||puts(""))
printf(M[i]?"%4d|":"    |",M[i]);
W-2||read(0,&k,3)|T(s (1,K[(k>>X)%4]));
}
//[2048] reformated 
Original Version : https://gist.github.com/justecorruptio/9967738
by : Jay Chan

I've reformatted the code a bit more, and added a few comments to explain some of the code. Please correct me if I'm wrong. (Unfortunately I don't know much about gist, so for now I'll leave the code here)

// Original file by Jay Chan:
// https://gist.github.com/justecorruptio/9967738

#include <stdio.h>
#define GRID_LEN 16

int M[GRID_LEN];
int X = GRID_LEN;
int W;
int k;

int K[] = {2, 3, 1};

s(f, d, i, j, l, P) {
    for(i = 4; i--;) {
        for(j = k = l = 0; k < 4;) {
            if(j < 4) {
                P = M[w(d, i, j++)];
                W |= P >> 11;
                l * P && (f ? M[w(d, i, k)] = l << (l == P) : 0, k++);
                l = l ? (P ? (l-P ? P : 0) : l) : P;
            }
            else {
                f ? M[ w(d, i, k) ] = l : 0;
                ++k;
                W |= 2 * !l;
                l = 0;
            }
        }
    }        
}

int w(d, i, j) {
    // Decrements until d reaches 0
    // Recursive function

    if(d <= 0) {
        return 4 * i + j;
    }

    return w(d - 1, j, 3 - i);
}

T(i) {
    for(i = X + rand() % X; M[i % X] * i; i--);
        i ? M[i % X] = 2 << rand() % 2: 0;

    for(W = i = 0; i < 4; i++) {
        s(0, i);
    }

    // Prints the tiles onto the terminal
    for(i = X, puts("\e[2J\e[H"); i--; i % 4 || puts("")) {
        printf(M[i] ? "%4d|":"    |", M[i]);
    }


    // Read input from keyboard
    W - 2 || read(0, &k, 3) | T(s (1, K[(k >> X) % 4]));
}

int main() {
    // Uses stty to clear the screen in preparation for the game
    T(system("stty cbreak"));

    // Game has finished by this point
    // If win, display "WIN". Otherwise, display "LOSE".
    puts(W & 1 ? "WIN" : "LOSE");
    return 0;
}

//[2048]

This passes gcc and clang without a warning.

Simplified the three functions T(), w() and s(); the arguments weren't passed in from outside, but were later initialised.
Unrolled the for-loops, sticking to the "1 statement per line" rule.

Added random seed.

// Original file by Jay Chan:
// https://gist.github.com/justecorruptio/9967738

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <time.h>

#define GRID_LEN 16

int M[GRID_LEN];
int X = GRID_LEN;
int W;
int k;
int K[] = { 2, 3, 1 };


int
w (int d, int i, int j)
{
  if (d <= 0) {
    return 4 * i + j;
  }

  return w (d - 1, j, 3 - i);
}

void
s (int f, int d)
{
  int i = 4, j, l, P;

  for (; i--;) {
    j = k = l = 0;

    for (; k < 4;) {
      if (j < 4) {
        P = M[w (d, i, j++)];
        W |= P >> 11;
        l *P && (f ? M[w (d, i, k)] = l << (l == P) : 0, k++);
        l = l ? (P ? (l - P ? P : 0) : l) : P;
      }
      else {
        f ? M[w (d, i, k)] = l : 0;
        ++k;
        W |= 2 * !l;
        l = 0;
      }
    }
  }
}

void
T ()
{
  int i = X + rand () % X;

  for (; M[i % X] * i; i--);

  i ? M[i % X] = 2 << rand () % 2 : 0;
  W = i = 0;

  for (; i < 4; i++) {
    s (0, i);
  }

  // Prints the tiles onto the terminal
  i = X;
  puts ("\e[2J\e[H");

  for (; i--;) {
    if (M[i]) {
      printf ("%4d|", M[i]);
    } else {
      printf ("%s", "    |");
    }

    // every 4th cell is followed by a line-break
    if (0 == (i & 3)) {
      putchar ('\n');
    }
  }

  // read input from keyboard
  if (!(W - 2)) {
    read (0, &k, 3);
    s (1, K[(k >> X) % 4]);
    T ();
  }
}

int
main (void)
{
  // Uses stty to clear the screen in preparation for the game
  system ("stty cbreak");

  /* Intializes random number generator */
  srand ((unsigned) time (NULL));

  T ();

  // Game has finished by this point
  // If win, display "WIN". Otherwise, display "LOSE".
  puts (W & 1 ? "WIN" : "LOSE");

  return 0;
}

I don't understand, why read(0,&k,3), the arrow keys only need 2 bytes.

The reason why 3 characters are read is that arrow keys generate 3-byte sequences.

Key	bytes	Hex value
arrow left	0x1b, '[', 'D'	0x1b5b44
arrow right	0x1b, '[', 'C'	0x1b5b43
arrow up	0x1b, '[', 'A'	0x1b5b41
arrow down	0x1b, '[', 'B'	0x1b5b42

When the characters are read, the 3-byte sequence actually is reversed.
So for instance, in the last case ('arrow down'), k is assigned 0x425b1b.

k is then used to decide which of the K-array value to use.
k is right-shifted by 16 bits, reducing it to 0x42, so we have K [ 0x042 % 4 ], which is equivalent to K[2], the 3rd element of K[].

Thus, the statement after the read (0, &k, 3) evaluates to calling s (1, 1).
I wonder why K[] does not have 4 values, one for each arrow key.

What is this mate i dont understand this code can u pls help me? I think w,a,s,d doesnt work for example i put w but numbers doesnt went up why?