https://www.luogu.org/problemnew/show/P1379
#include<algorithm> #include<set> #include<vector> #include<queue> #include<cmath> #include<cstring> #include<iostream> #include<set> #include<vector> #include<queue> #include<cmath> #include<cstring> #include<sstream> #include<cstdio> #include<ctime> #include<map> #include<stack> #include<string> #include<ctime> using namespace std; #define sfi(i) scanf("%d",&i) #define pri(i) printf("%d\n",i) #define sff(i) scanf("%lf",&i) #define ll long long #define mem(x,y) memset(x,y,sizeof(x)) #define INF 0x3f3f3f3f #define eps 1e-14 #define PI acos(-1) #define lowbit(x) ((x)&(-x)) #define zero(x) (((x)>0?(x):-(x))<eps) #define fl() printf("flag\n") #define MOD(x) ((x%mod)+mod)%mod #define FASTIO ios::sync_with_stdio(false);cin.tie(0);cout.tie(0); ll gcd(ll a,ll b){while(b^=a^=b^=a%=b);return a;} const int maxn=1e6+9; const int mod=1e8+7; inline ll read() { ll f=1,x=0; char ss=getchar(); while(ss<'0'||ss>'9'){if(ss=='-')f=-1;ss=getchar();} while(ss>='0'&&ss<='9'){x=x*10+ss-'0';ss=getchar();} return f*x; } int gol[10]={5,1,2,3,6,9,8,7,4}; int dis[11][11]; int now[10]; int mp[11][11],tmp[11][11]; int dx[5]={0,0,1,-1}; int dy[5]={1,-1,0,0}; bool f=0; int h() { int sum=0; for(int i=1;i<9;i++) { sum+=dis[now[i]][gol[i]]; } return sum; } bool ch() { for(int i=0;i<9;i++) if(now[i]!=gol[i]) return 0; return 1; } void mdis() { for(int i=1;i<=9;i++) { for(int j=1;j<=9;j++) { int jj=j%3?j%3:3; int ii=i%3?i%3:3; dis[i][j]=abs((i-1)/3-(j-1)/3)+abs(jj-ii); } } } void dfs(int g,int x,int y,int st) { if(f) return ; if(g+h()>st) return ; if(ch()) { f=1; return ; } for(int i=0;i<4;i++) { int tx=x+dx[i]; int ty=y+dy[i]; if(tx>=1&&ty>=1&&tx<=3&&ty<=3) { swap(tmp[x][y],tmp[tx][ty]); swap(now[tmp[x][y]],now[tmp[tx][ty]]); dfs(g+1,tx,ty,st); swap(tmp[x][y],tmp[tx][ty]); swap(now[tmp[x][y]],now[tmp[tx][ty]]); } } } int main() { //FASTIO; //#define endl '\n' mdis(); string s; int cnt=0; cin>>s; int sx=0,sy=0; for(int i=1;i<=3;i++) { for(int j=1;j<=3;j++) { int k=s[cnt++]-'0'; mp[i][j]=k; if(k==0) sx=i,sy=j; now[k]=(i-1)*3+j; } } int st=0; while(1) { memcpy(tmp,mp,sizeof(mp)); dfs(0,sx,sy,st); if(f) { cout<<st<<endl; break; } st++; } return 0; }