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#include <stdio.h>
#include <string.h>
#include <iostream>
#include <math.h>
#include <stdlib.h>
using namespace std;
#define DOWN 0
#define UP 1
#define LEFT 2
#define RIGHT 3
class puzzle {
private:
struct state
{
int block[9];
char* str;
int pathcost;
int valid;
int totalcost;
state* next;
};
char rep[4] = {'d','u','l','r'};
int notvalid1[4] = { 6, 0, 0, 2 };
int notvalid2[4] = { 7, 1, 3, 5 };
int notvalid3[4] = { 8, 2, 6, 8 };
int applyparam[4] = { +3, -3, -1, +1 };
int goal_block[9] = { 0, 1, 2, 3, 4, 5, 6, 7, 8}; //8 indicates no tile
const int maxdepth = 31;
int block[9];
state* top;
public:
int h(int block[])
{
int manCounter = 0;
for(int i=0; i<9; i++)
{
manCounter += abs((i/3) - (block[i]/3));
manCounter += abs((i%3) - (block[i]%3));
}
return manCounter;
}
void prepend(state* newnode, state* oldnode, int op)
{
newnode->next = top;
top = newnode;
newnode->str = oldnode->str;
newnode->str[oldnode->pathcost] = rep[op];
newnode->str[oldnode->pathcost+1] = 0;
newnode->pathcost = oldnode->pathcost+1;
newnode->totalcost = newnode->pathcost + h(newnode->block);
if (newnode->totalcost < oldnode->totalcost) newnode->totalcost = oldnode->totalcost;
}
int goal(int* block)
{
int* g_block = goal_block;
for(int i=0; i<9; i++)
if ((*(block++))!=(*(g_block++)))
return 0;
return 1;
}
int notonqueue(int block[])
{
int i;
state* t = top;
while (t != NULL)
{
for(i = 0; i < 9; i++) {
if (t->block[i] != block[i])
break;
}
if (i==9)
return 0;
t = t->next;
}
return 1;
}
state* bestnodefromqueue()
{
state* t = top;
int min_totalpathcost = 1000;
state* to_return = NULL;
while (t != NULL)
{
if (t->valid==1 && t->totalcost < min_totalpathcost)
{
min_totalpathcost = t->totalcost;
to_return = t;
}
t = t->next;
}
if (to_return != NULL)
to_return->valid = 0;
return to_return;
}
void print_block(int* block)
{
for (int i = 0; i < 9; i++) {
cout << to_char(block[i]);
}
cout << endl;
}
int apply (int* newstate, int* oldstate, int op)
{
int j;
int blank;
for (j=0; j<9; j++) {
if (oldstate[j]==8)
{
blank=j;
break;
}
}
if (blank==notvalid1[op] || blank==notvalid2[op] || blank==notvalid3[op])
return -1;
for (j=0; j<9; j++)
newstate[j] = oldstate[j];
newstate[blank] = newstate[blank+applyparam[op]];
newstate[blank+applyparam[op]] = 8;
return 1;
}
state* newelement()
{
state* t = new state;
if (t==NULL)
{
return NULL;
}
t->valid = 1;
t->str = new char[maxdepth+1];
if (t->str ==NULL){
return NULL;
}
t->str[0] = 0;
t->pathcost = t->totalcost = 0;
t->next = NULL;
return t;
}
char to_char(int i)
{
if (i>=0 &&i<=7) return i+'1';
else if (i==8) return '0';
else { printf("ERROR in Program!"); return -1; }
}
int op(char i)
{
switch (i)
{
case 'd': return 0;
case 'u': return 1;
case 'l': return 2;
case 'r': return 3;
default:
cout << "ERROR!";
return -1;
}
}
void setStart() {
int i = 0;
string intstate;
cout << "Enter the start state: ";
cin >> intstate;
while(i<9)
{
if (intstate[i] == '0') {
block[i] = 8;
}
else if (intstate[i] >= '1' && intstate[i] <= '9') {
block[i] = intstate[i] - '1';
}
else
{
cout << "Invalid Input" << endl;
}
i++;
}
}
void setGoal() {
int i = 0;
string goalstate = "012345678";
while (i < 9) {
if (goalstate[i] == '0')
goal_block[i] = 8;
else if (goalstate[i] >= '1' && goalstate[i] <= '9')
goal_block[i] = goalstate[i] - '1';
i++;
}
}
void successor() {
top = newelement();
for(int i = 0; i < 9; i++) {
top->block[i] = block[i];
}
top->totalcost = h(block);
state* newnode = newelement();
while (1)
{
state* node = bestnodefromqueue();
if (node == NULL) {
cout << "If there is no solution." << endl;
break;
}
else if (goal(node->block)) {
int block2[9];
for (int i = 0; i < node->pathcost; i++)
{
print_block(block);
apply(block2, block, op(node->str[i]));
for(int j=0; j<=8; j++)
block[j] = block2[j];
}
print_block(block);
break;
}
if (node->totalcost > maxdepth) continue;
for(int i=0; i<=3; i++) {
if (apply(newnode->block, node->block, i) == -1)
continue;
if (notonqueue(newnode->block)) {
prepend(newnode, node, i);
newnode = newelement();
if (newnode==NULL) {
cout << "ERROR!! insufficient memory!!" << endl;
}
}
}
}
}
};
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