rt，我感觉没啥问题，求助大佬们。

题目：

代码：

#include <iostream>
#include <cstdio>
#include <cstring>
#include <queue>

using namespace std;

const int N = 4;

int sx, sy;
int g[N][N], wish[N][N] = {{0, 0, 1, 2}, {0, 3, 4, 5}, {0, 6, 7, 8}};
bool ju;
int depth;
int dx[] = {0, 0, 1, -1}, dy[] = {1, -1, 0, 0};

bool ck()
{
	for (int i = 1; i <= 3; i ++ )
	  for (int j = 1; j <= 3; j ++ )
	    if (g[i][j] != wish[i][j])
	      return 0;
	
	return 1;
}

bool f(int rip)
{
	int cnt = 0;
	for (int i = 1; i <= 3; i ++ )
	  for (int j = 1; j <= 3; j ++ )
	    if (wish[i][j] != g[i][j])
	    {
			cnt ++ ;
			if (cnt + rip > depth) return 0;
		}
	return 1;
}

void dfs(int step, int x, int y, int pre)
{
	if (step == depth)
	{
		if (ck()) {ju = 1;printf("%d\n", depth);exit(0);}
		return;
	}
	if (ju) return;
	
	for (int i = 0; i < 4; i ++ )
	{
		int a = x + dx[i], b = y + dy[i];
		if (a < 1 || b < 1 || a > 3 || b > 3 || pre + i == 3) continue;
		swap(g[a][b], g[x][y]);
		if (!ju && f(step)) dfs(step + 1, a, b, i);
		swap(g[x][y], g[a][b]);
	}
}

int main()
{
	for (int i = 1; i <= 3; i ++ )
	  for (int j = 1; j <= 3; j ++ )
	  {
	  	scanf("%d", &g[i][j]);
	  	if (g[i][j] == 0) sx = i, sy = j;
	  }
	
	if (ck()) {puts("0");return 0;}
	while (!ju) 
	{
		depth ++ ;
		dfs(0, sx, sy, -1);
		if (ju)
		{
			printf("%d\n", depth);
			return 0;
		}
	}
	return 0;
}