单向和双向bfs
1 #include<iostream> 2 #include<cstdio> 3 #include<queue> 4 #include<algorithm> 5 #include<cmath> 6 #include<ctime> 7 #include<set> 8 #include<map> 9 #include<stack> 10 #include<cstring> 11 #define inf 2147483647 12 #define ls rt<<1 13 #define rs rt<<1|1 14 #define lson ls,nl,mid,l,r 15 #define rson rs,mid+1,nr,l,r 16 #define N 100010 17 #define For(i,a,b) for(register int i=a;i<=b;i++) 18 #define p(a) putchar(a) 19 #define g() getchar() 20 21 using namespace std; 22 int n,temp; 23 int dx[]={-1,1,0,0}; 24 int dy[]={0,0,-1,1}; 25 int a[10][10]; 26 map<int,int>m; 27 queue<int>q; 28 int t,x,y,nx,ny; 29 void in(int &x){ 30 int y=1; 31 char c=g();x=0; 32 while(c<'0'||c>'9'){ 33 if(c=='-')y=-1; 34 c=g(); 35 } 36 while(c<='9'&&c>='0'){ 37 x=(x<<1)+(x<<3)+c-'0';c=g(); 38 } 39 x*=y; 40 } 41 void o(int x){ 42 if(x<0){ 43 p('-'); 44 x=-x; 45 } 46 if(x>9)o(x/10); 47 p(x%10+'0'); 48 } 49 50 inline void Turn(int n){ 51 for(register int i=3;i;i--) 52 for(register int j=3;j;j--){ 53 a[i][j]=n%10; 54 n/=10; 55 if(!a[i][j]){ 56 x=i; 57 y=j; 58 } 59 } 60 } 61 62 int main(){ 63 in(n); 64 q.push(n); 65 while(!q.empty()){ 66 t=q.front();q.pop(); 67 if(t==123804765) 68 break; 69 Turn(t); 70 For(I,0,3){ 71 nx=x+dx[I]; 72 ny=y+dy[I]; 73 if(nx>3||ny>3||nx<1||ny<1) continue; 74 swap(a[nx][ny],a[x][y]); 75 temp=0; 76 For(i,1,3) 77 For(j,1,3){ 78 temp*=10; 79 temp+=a[i][j]; 80 } 81 if(!m.count(temp)){ 82 m[temp]=m[t]+1; 83 q.push(temp); 84 } 85 swap(a[nx][ny],a[x][y]); 86 } 87 } 88 o(m[123804765]); 89 return 0; 90 }
1 #include<iostream> 2 #include<cstdio> 3 #include<queue> 4 #include<algorithm> 5 #include<cmath> 6 #include<ctime> 7 #include<set> 8 #include<map> 9 #include<stack> 10 #include<cstring> 11 #define inf 2147483647 12 #define ls rt<<1 13 #define rs rt<<1|1 14 #define lson ls,nl,mid,l,r 15 #define rson rs,mid+1,nr,l,r 16 #define N 123804765 17 #define For(i,a,b) for(int i=a;i<=b;i++) 18 #define p(a) putchar(a) 19 #define g() getchar() 20 21 using namespace std; 22 int n,temp; 23 int dx[]={-1,1,0,0}; 24 int dy[]={0,0,-1,1}; 25 int a[10][10]; 26 map<int,int>m,d; 27 28 queue<int>q; 29 int t,x,y,nx,ny; 30 void in(int &x){ 31 int y=1; 32 char c=g();x=0; 33 while(c<'0'||c>'9'){ 34 if(c=='-')y=-1; 35 c=g(); 36 } 37 while(c<='9'&&c>='0'){ 38 x=(x<<1)+(x<<3)+c-'0';c=g(); 39 } 40 x*=y; 41 } 42 void o(int x){ 43 if(x<0){ 44 p('-'); 45 x=-x; 46 } 47 if(x>9)o(x/10); 48 p(x%10+'0'); 49 } 50 51 inline void Turn(int n){ 52 for(int i=3;i;i--) 53 for(int j=3;j;j--){ 54 a[i][j]=n%10; 55 n/=10; 56 if(!a[i][j]){ 57 x=i; 58 y=j; 59 } 60 } 61 } 62 63 int main(){ 64 in(n); 65 if(n==N){ 66 o(0); 67 return 0; 68 } 69 q.push(n); 70 q.push(N); 71 m[N]=1; 72 d[n]=1; 73 d[N]=2; 74 while(!q.empty()){ 75 t=q.front();q.pop(); 76 Turn(t); 77 For(I,0,3){ 78 nx=x+dx[I]; 79 ny=y+dy[I]; 80 if(nx>3||ny>3||nx<1||ny<1) continue; 81 swap(a[nx][ny],a[x][y]); 82 temp=0; 83 For(i,1,3) 84 For(j,1,3){ 85 temp*=10; 86 temp+=a[i][j]; 87 } 88 if(d[temp]==d[t]){ 89 swap(a[nx][ny],a[x][y]); 90 continue; 91 } 92 if(d[temp]+d[t]==3){ 93 o(m[temp]+m[t]); 94 return 0; 95 } 96 d[temp]=d[t]; 97 m[temp]=m[t]+1; 98 q.push(temp); 99 swap(a[nx][ny],a[x][y]); 100 } 101 } 102 return 0; 103 }