这题与前面的“踩方格”重复了，而且是大坑题！题目漏写了取模12345的条件！
详细解析请见我之前的博文——http://www.cnblogs.com/konjak/p/5936888.html
而这坑在我打了高精+滚动之后才知道。。我先把这个代码贴上来。。
1 #include<cstdio> 2 #include<cstdlib> 3 #include<cstring> 4 #include<iostream> 5 using namespace std; 6 7 struct node{int s[510];int l;} 8 f[3],c;//1010 9 10 int mmax(int x,int y) {return x>y?x:y;} 11 node pplus(node a,node b) 12 { 13 c.l=mmax(a.l,b.l); 14 memset(c.s,0,sizeof(c.s)); 15 for (int i=1;i<=c.l;i++) 16 { 17 c.s[i]+=a.s[i]+b.s[i]; 18 c.s[i+1]+=c.s[i]/10; 19 c.s[i]%=10; 20 } 21 if (c.s[c.l+1]) c.l++; 22 return c; 23 } 24 25 int main() 26 { 27 int n; 28 scanf("%d",&n); 29 f[1].l=1,f[1].s[1]=3; 30 f[2].l=1,f[2].s[1]=7; 31 int u,v,w; 32 u=0; 33 for (int i=3;i<=n;i++) 34 { 35 v=(u+2)%3,w=(u+1)%3;//v=(u+3-1)%3,w=(u+3-2)%3; 36 f[u]=pplus(pplus(f[v],f[v]),f[w]); 37 u=(u+1)%3; 38 }//f[i]=pplus(pplus(f[i-1],f[i-1]),f[i-2]); 39 int t=(u+2)%3;//(u+3-1)%3; 40 if (n<3) t=n; 41 for (int i=f[t].l;i>=1;i--) 42 printf("%d",f[t].s[i]); 43 printf(" "); 44 return 0; 45 }
AC代码是这样的——
1 #include<cstdio> 2 #include<cstdlib> 3 #include<cstring> 4 #include<iostream> 5 using namespace std; 6 7 int f[3]; 8 int main() 9 { 10 int n; 11 scanf("%d",&n); 12 f[1]=3, f[2]=7; 13 int u,v,w; 14 u=0; 15 for (int i=3;i<=n;i++) 16 { 17 v=(u+2)%3,w=(u+1)%3; 18 f[u]=(2*f[v]+f[w])%12345; 19 u=(u+1)%3; 20 } 21 if (n<3) printf("%d ",f[n]); 22 else printf("%d ",f[(u+2)%3]); 23 return 0; 24 }
1 #include<cstdio> 2 #include<cstdlib> 3 #include<cstring> 4 #include<iostream> 5 using namespace std; 6 7 long long f[1010]; 8 9 int main() 10 { 11 int n; 12 scanf("%d",&n); 13 f[1]=3, f[2]=7; 14 for (int i=3;i<=n;i++) 15 f[i]=(2*f[i-1]+f[i-2])%12345; 16 printf("%lld ",f[n]); 17 return 0; 18 }