[bzoj] 1085 骑士精神 || ID-DFS

原题

找到最少的步数成为目标状态。

---

IDDFS（限制层数的dfs）即可

#include<cstdio>
#include<algorithm>
using namespace std;
int t,n,m,disx[10]={0,1,2,2,1,-1,-2,-2,-1},disy[10]={0,2,1,-1 ,-2,-2,-1,1,2},posx,posy,ans;
char a[8][8];

int read()
{
    int ans=0,fu=1;
    char j=getchar();
    for (;(j<'0' || j>'9') && j!='-';j=getchar()) ;
    if (j=='-') j=getchar(),fu=-1;
    for (;j>='0' && j<='9';j=getchar()) ans*=10,ans+=j-'0';
    return ans*fu;
}

int chk()
{
    int cnt;
    if (a[3][3]!='*') cnt=1;
    for (int i=1;i<=5;i++)
	for (int j=i+(i>=3);j<=5;j++)
	    if (a[i][j]=='0') cnt++;
    for (int i=5;i>=1;i--)
	for (int j=1;j<=i-(i<=3);j++)
	    if (a[i][j]=='1') cnt++;
    return cnt;
}

bool check()
{
    for (int i=1;i<=5;i++)
	for (int j=i+(i>=3);j<=5;j++)
	    if (a[i][j]=='0') return 0;
    for (int i=5;i>=1;i--)
	for (int j=1;j<=i-(i<=3);j++)
	    if (a[i][j]=='1') return 0;
    return 1;
}

bool illegal(int x,int y)
{
    if (x<1 || y<1) return 1;
    if (x>5 || y>5) return 1;
    return 0;
}

void dfs(int x,int px,int py)
{
    if (!x)
    {
	if (px==3 && py==3 && check()) ans=1;
	return ;
    }
    for (int i=1;i<=8;i++)
    {
	int vx,vy;
	vx=px+disx[i];
	vy=py+disy[i];
	if (illegal(vx,vy)) continue;
	swap(a[vx][vy],a[px][py]);
	if (chk()<=x) dfs(x-1,vx,vy);
	swap(a[vx][vy],a[px][py]);
    }
}

int main()
{
    t=read();
    while (t--)
    {
	ans=0;
	for (int i=1;i<=5;i++)
	{
	    for (int j=1;j<=5;j++)
	    {
		a[i][j]=getchar();
		if (a[i][j]=='*') posx=i,posy=j;
	    }
	    getchar();
	}
	for (int i=0;i<=15;i++)
	{
	    dfs(i,posx,posy);
	    if (ans)
	    {
		printf("%d
",i);
		break;
	    }
	}
	if (!ans) printf("-1
");
    }
    return 0;
}