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

void left(int );
void right(int);
void up(int );
void down(int );

void print_state(int [][]);
void get_state(int [][]);

// code for actions: 0 - right, 1 - left, 2 - down, 3 - up


typedef struct board
{
  int state[3][3];
  int moves[100]; 
  int NUMBER_OF_MOVES;
  int h2;
  int done;
} BOARD;


BOARD rt[200000];
int   curMax = 0;
int   goal_state[3][3];


void add_one(BOARD, int);
int  h2(int [][]);
void expand();


int main()
{
    int i, j;
    int initial_state[3][3];
    BOARD b;

    printf("Input the initial state\n");
    get_state(initial_state);
 
    printf("Input the goal state\n");
    get_state(goal_state);

    print_state(initial_state);
    printf("\n");
    print_state(goal_state);

    for(i=0 ; i<3 ; i++)
    {
        for(j=0 ; j<3 ; j++)
            b.state[i][j] = initial_state[i][j];
    }
   
    b.NUMBER_OF_MOVES = 0;
    b.h2 = h2(b.state);

    //printf("Heuristic h2 for the initial state %d\n", h2(initial_state));

    //printf("Heuristic h2 for the goal state %d\n", h2(goal_state));

    add_one(b, -1);

    //printf("\n");
    // print_state(rt[0].state);
            
    //printf("Heuristic h2 for the initial state %d\n", rt[0].h2);

    expand();

    /*
    for(i = 0; i < curMax; i++){
      printf("\n");
      print_state(rt[i].state);
      printf("Heuristic h2 for this state %d - done expanding %d\n", rt[i].h2,rt[i].done);
      
    }
    */

    return 0;

}


void print_solution(int cnt)
{
  BOARD b = rt[cnt];
  int i;

  print_state(b.state);
 
   for(i=0; i<b.NUMBER_OF_MOVES; i++){
    printf("Move %d %d\n",i,b.moves[i]);
  }   

  printf("Here ...");
}


void expand()
{
  int i, bToExpand = 0;
  int minH2, j; 

for(;curMax < 181439 ; ){

  for(i = 0; i < curMax; i++){
    if (rt[i].done==0) {minH2 = rt[i].h2; bToExpand = i; break;}    
  }


  for(i = 0; i < curMax; i++){
    if (rt[i].h2 == 0){
      bToExpand = i;  
      break;
    }
    
     
    if (rt[i].h2 < minH2 && rt[i].done==0){
      bToExpand = i;  
      minH2 = rt[i].h2;
    }
  }

  if (rt[bToExpand].h2 == 0) {
      print_solution(bToExpand);
    break;
  }

  // expanding node bToExpand

  printf("Note to expand %d\n",bToExpand);
  print_state(rt[bToExpand].state);
  printf("h2 --> %d -- No of moves %d\n",rt[bToExpand].h2,rt[bToExpand].NUMBER_OF_MOVES);


  left(bToExpand);
  right(bToExpand);
  down(bToExpand);
  up(bToExpand);
  
  rt[bToExpand].done = 1;

}
}


void left(int cnt)
{
  int i,j,found = 0;
  BOARD b = rt[cnt];

  if (b.state[0][0]==0 || b.state[1][0]==0 || b.state[2][0]==0) return;

  for (i=0; i<3 ; i++){
    for(j=0; j<3; j++){
      if (b.state[i][j] == 0){
	b.state[i][j] = b.state[i][j-1];
	b.state[i][j-1] = 0;
        found = 1;
        break;         
      }
    }
    if (found == 1) break;
  }  

  b.h2 = b.NUMBER_OF_MOVES + h2(b.state);

  add_one(b, 1);

}


void right(int cnt)
{
  int i,j,found = 0;
  BOARD b = rt[cnt];

  if (b.state[0][2]==0 || b.state[1][2]==0 || b.state[2][2]==0) return;

  for (i=0; i<3 ; i++){
    for(j=0; j<3; j++){
      if (b.state[i][j] == 0){
	b.state[i][j] = b.state[i][j+1];
	b.state[i][j+1] = 0;
        found = 1;
        break;         
      }
    }
    if (found == 1) break;
  }  

  b.h2 = b.NUMBER_OF_MOVES + h2(b.state);

  add_one(b, 0);
}

void down(int cnt)
{
  int i,j,found = 0;
  BOARD b = rt[cnt];

  if (b.state[2][0]==0 || b.state[2][1]==0 || b.state[2][2]==0) return;

  for (i=0; i<3 ; i++){
    for(j=0; j<3; j++){
      if (b.state[i][j] == 0){
	b.state[i][j] = b.state[i+1][j];
	b.state[i+1][j] = 0;
        found = 1;
        break;         
      }
    }
    if (found == 1) break;
  }  

  b.h2 = b.NUMBER_OF_MOVES + h2(b.state);

  add_one(b, 2);
}

void up(int cnt)
{
  int i,j,found = 0;
  BOARD b = rt[cnt];

  if (b.state[0][0]==0 || b.state[0][1]==0 || b.state[0][2]==0) return;

  for (i=0; i<3 ; i++){
    for(j=0; j<3; j++){
      if (b.state[i][j] == 0){
	b.state[i][j] = b.state[i-1][j];
	b.state[i-1][j] = 0;
        found = 1;
        break;         
      }
    }
    if (found == 1) break;
  }  

  b.h2 = b.NUMBER_OF_MOVES + h2(b.state);

  add_one(b, 3);
}


int h2(int state[][3])
{
  int i, j, k, l;
  int current, found;
  int counter = 0;
  


  for(i=0; i<3; i++){
    for(j=0; j<3; j++){
      current = state[i][j];
      found = 0;
      //    printf("%d ", current);
      for(k=0; k<3; k++){
        for(l=0; l<3; l++){
          if (current == goal_state[k][l]){
	    found = 1;
            break;
          } 
	}
        if (found==1) break;
      }
      counter = counter + abs(i-k)+abs(j-l);
      // printf("%d \n", counter);
    }   
  }


  // add h1 to h2

  return counter;

}



void add_one(BOARD b, int code)
{
    int i,j;
    int k,l;
    int found;

    found = 0;
    for(i = 0; i<curMax; i++){
      found = 0;
      for(j = 0; j<3; j++){
        for(k = 0; k < 3; k++)
	  if (rt[i].state[j][k] == b.state[j][k]) found++;
      }
      if(found == 9) break;
    }     
    if(found == 9) return;

    for(i=0 ; i<3 ; i++)
    {
        for(j=0 ; j<3 ; j++)
            rt[curMax].state[i][j] = b.state[i][j];
    }

    for(i=0; i<b.NUMBER_OF_MOVES; i++)
      rt[curMax].moves[i] = b.moves[i];

    rt[curMax].done = 0;

    if (code != -1){
      rt[curMax].moves[b.NUMBER_OF_MOVES] = code;
      rt[curMax].NUMBER_OF_MOVES = b.NUMBER_OF_MOVES + 1;
    }
    else 
      rt[curMax].NUMBER_OF_MOVES = b.NUMBER_OF_MOVES;

    rt[curMax].h2 = b.h2;

    curMax ++;
} 


void print_state(int state[][3])
{
    int i,j;

    for(i=0 ; i<3 ; i++)
    {
        for(j=0 ; j<3 ; j++)
            printf("%d ",state[i][j]);
        printf("\n");
    }
}

void get_state(int state[][3])
{
    int i,j;

    for(i=0 ; i<3 ; i++)
        for(j=0 ; j<3 ; j++)
        {
            printf("Input element [%d][%d] of the state:\n",i+1,j+1);
            scanf("%d",&state[i][j]);
        }
}