刚开始看到此题，以为是bfs，便高高兴兴的写了一堆。。。
不幸的事发生了，tle，只得仔细撕烤。
突然发现找到一个数字可以变化的次数和，之后在连续乘起来 得到的结果就是变化次数。
高精警告
40分tle：
1 // luogu-judger-enable-o2 2 #include<bits/stdc++.h> 3 namespace ZDY{ 4 #define fir freopen("2.in","r",stdin) 5 #define ll long long 6 #define db double 7 #define Fur(i,x,y) for(int i=x;i<=y;i++) 8 #define fur(i,x,y) for(i=x;i<=y;i++) 9 #define Fdr(i,x,y) for(int i=x;i>=y;i--) 10 #define in2(x,y) in(x),in(y) 11 #define in3(x,y,z) in2(x,y),in(z) 12 #define in4(a,b,c,d) in2(a,b);in2(c,d) 13 #define clr(x,y) memset(x,y,sizeof(x)) 14 #define cpy(x,y) memcpy(x,y,sizeof(x)) 15 #define fl(i,x) for(ll i=head[x],to;to=e[i].to,i;i=e[i].next) 16 #define inf 2147483647 17 } 18 namespace FAST{ 19 #define pob (fwrite(fob::b,sizeof(char),fob::f-fob::b,stdout),fob::f=fob::b,0) 20 #define pc(x) (*(fob::f++)=(x),(fob::f==fob::g)?pob:0) 21 #define gc ((*fib::f)?(*(fib ::f++)):(fgets(fib::b,sizeof(fib::b),stdin)?(fib::f=fib::b,*(fib::f++)):-1)) 22 namespace fib{char b[300000]= {},*f=b;}namespace fob{char b[300000]= {},*f=b,*g=b+300000-2;}struct foce{~foce(){pob;fflush(stdout);}} _foce;namespace ib{char b[100];}template<class T>inline void in(T &x){x=0;char c;bool f=0;while((c=gc)>'9'||c<'0')if(c=='-')f=!f;x=c-48;while((c=gc)<='9'&&c>='0')x=x*10+c-48;if(f)x=-x;}template<class T>inline void out(T x){if(x==0){pc(48);return;}if(x<0){pc('-');x=-x;}char *s=ib::b;while(x) *(++s)=x%10,x/=10;while(s!=ib::b) pc((*(s--))+48);}template<class T>inline void outn(T x){out(x);pc(' ');} 23 inline char sc(){char c=gc;while(!(('A'<=c&&c<='Z')||('a'<=c&&c<='z')||('0'<=c<='9')))c=gc;return c;} 24 template<class T>inline T ABS(T x){return x>0?x:-x;} 25 template<class T>inline T MAX(T x,T y){return x>y?x:y;} 26 template<class T>inline T MIN(T x,T y){return x<y?x:y;} 27 template<class T>inline T GCD(T x,T y){return y?GCD(y,x%y):x;} 28 template<class T>inline void swap(T x,T y){T t=x;y=t;x=y;} 29 }using namespace FAST;using namespace ZDY;using namespace std; 30 #define N 1000001 31 #define mod 83958397 32 int h=0,t=1,k,d=0,cnt=0,ans=0,head[11]; 33 bool v[mod]; 34 struct edge{int next,to;}e[30]; 35 struct sz{int s[32];}q[N]; 36 inline void add(int x,int y){e[++cnt].to=y;e[cnt].next=head[x];head[x]=cnt;} 37 inline int hash(sz x){ 38 int s=0; 39 Fur(i,1,d)s=(s*10+x.s[i])%mod; 40 return s; 41 } 42 inline void bfs(){ 43 sz x; 44 int u,ha; 45 while(h<t){ 46 x=q[h++]; 47 Fur(j,1,d)fl(i,x.s[j]){ 48 u=x.s[j];x.s[j]=to; 49 ha=hash(x); 50 if(!v[ha])v[ha]=1,q[t++]=x,ans++; 51 x.s[j]=u; 52 } 53 } 54 } 55 int main(){ 56 char c=gc; 57 while(c<'0'||'9'<c)c=gc; 58 while('0'<=c&&c<='9')q[0].s[++d]=c-48,c=gc; 59 ans=1;v[hash(q[0])]=1; 60 in(k); 61 int x,y; 62 Fur(i,1,k)in2(x,y),add(x,y); 63 bfs(); 64 outn(ans); 65 }
ac 0ms：
1 // luogu-judger-enable-o2 2 #include<bits/stdc++.h> 3 namespace ZDY{ 4 #define fir freopen("2.in","r",stdin) 5 #define ll long long 6 #define db double 7 #define Fur(i,x,y) for(int i=x;i<=y;i++) 8 #define fur(i,x,y) for(i=x;i<=y;i++) 9 #define Fdr(i,x,y) for(int i=x;i>=y;i--) 10 #define in2(x,y) in(x),in(y) 11 #define in3(x,y,z) in2(x,y),in(z) 12 #define in4(a,b,c,d) in2(a,b);in2(c,d) 13 #define clr(x,y) memset(x,y,sizeof(x)) 14 #define cpy(x,y) memcpy(x,y,sizeof(x)) 15 #define fl(i,x) for(ll i=head[x],to;to=e[i].to,i;i=e[i].next) 16 #define inf 2147483647 17 } 18 namespace FAST{ 19 #define pob (fwrite(fob::b,sizeof(char),fob::f-fob::b,stdout),fob::f=fob::b,0) 20 #define pc(x) (*(fob::f++)=(x),(fob::f==fob::g)?pob:0) 21 #define gc ((*fib::f)?(*(fib ::f++)):(fgets(fib::b,sizeof(fib::b),stdin)?(fib::f=fib::b,*(fib::f++)):-1)) 22 namespace fib{char b[300000]= {},*f=b;}namespace fob{char b[300000]= {},*f=b,*g=b+300000-2;}struct foce{~foce(){pob;fflush(stdout);}} _foce;namespace ib{char b[100];}template<class T>inline void in(T &x){x=0;char c;bool f=0;while((c=gc)>'9'||c<'0')if(c=='-')f=!f;x=c-48;while((c=gc)<='9'&&c>='0')x=x*10+c-48;if(f)x=-x;}template<class T>inline void out(T x){if(x==0){pc(48);return;}if(x<0){pc('-');x=-x;}char *s=ib::b;while(x) *(++s)=x%10,x/=10;while(s!=ib::b) pc((*(s--))+48);}template<class T>inline void outn(T x){out(x);pc(' ');} 23 inline char sc(){char c=gc;while(!(('A'<=c&&c<='Z')||('a'<=c&&c<='z')||('0'<=c<='9')))c=gc;return c;} 24 template<class T>inline T ABS(T x){return x>0?x:-x;} 25 template<class T>inline T MAX(T x,T y){return x>y?x:y;} 26 template<class T>inline T MIN(T x,T y){return x<y?x:y;} 27 template<class T>inline T GCD(T x,T y){return y?GCD(y,x%y):x;} 28 template<class T>inline void swap(T x,T y){T t=x;y=t;x=y;} 29 }using namespace FAST;using namespace ZDY;using namespace std; 30 #define N 10000001 31 #define mod 83958397 32 bool b[10][10]; 33 int n,f[10],p[1001]={1},lp=1; 34 char a[32]; 35 inline void c(int x){ 36 Fur(i,0,lp-1)p[i]*=x; 37 Fur(i,0,lp-1)if(p[i]>9)p[i+1]+=p[i]/10,p[i]%=10; 38 while(p[lp]){if(p[lp]>9)p[lp+1]+=p[lp]/10,p[lp]%=10;lp++;} 39 } 40 int main(){ 41 scanf("%s",a); 42 in(n); 43 int x,y; 44 Fur(i,1,n)in2(x,y),b[x][y]=1; 45 Fur(k,1,9)Fur(i,0,9)Fur(j,1,9)if(i!=k&&k!=j)b[i][j]|=b[i][k]&&b[k][j]; 46 Fur(i,0,9){ 47 b[i][i]=1; 48 Fur(j,0,9)if(b[i][j])f[i]++; 49 } 50 Fur(i,0,strlen(a)-1)c(f[a[i]-48]); 51 Fdr(i,lp-1,0)pc(p[i]+48); 52 }