七个for。或者写成DP。
//#pragma comment(linker, "/STACK:1024000000,1024000000") #include<cstdio> #include<cstring> #include<cstdlib> #include<algorithm> #include<iostream> #include<sstream> #include<cmath> #include<climits> #include<string> #include<map> #include<queue> #include<vector> #include<stack> #include<set> using namespace std; typedef long long ll; typedef pair<int,int> pii; #define pb(a) push_back(a) #define INF 0x1f1f1f1f #define lson idx<<1,l,mid #define rson idx<<1|1,mid+1,r #define PI 3.1415926535898 template<class T> T min(const T& a,const T& b,const T& c) { return min(min(a,b),min(a,c)); } template<class T> T max(const T& a,const T& b,const T& c) { return max(max(a,b),max(a,c)); } #define clr0(a) memset(a,0,sizeof(a)) #define clr1(a) memset(a,-1,sizeof(a)) void debug(){ #ifdef ONLINE_JUDGE #else freopen("d:\in.txt","r",stdin); // freopen("d:\out1.txt","w",stdout); #endif } int getch() { char ch; // while((ch=getchar())!=EOF) // { // if(ch!=' '&&ch!=' ')return ch; // } scanf(" %c",&ch); return ch; } int vis[50][10]; double dp[50][10]; double f(int n,int res) { if(res==0) { if(n==0)return 1; else return 0; } if(vis[n][res])return dp[n][res]; vis[n][res]=1; double x=0; for(int i=1;i<=6;i++) { if(n-i>=0) x+=f(n-i,res-1)/6; } return dp[n][res]=x; } int main() { int n; while(scanf("%d",&n)!=EOF) { memset(vis,0,sizeof(dp)); printf("%.4lf ",f(n,7)); } return 0; }