HDU-5793-A Boring Question(打表找规律)
2016-08-04 17:35
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链接:http://acm.hdu.edu.cn/showproblem.php?pid=5793
题意:推公式
题解:打表找规律
CODE:
找规律代码QAQ:
#include <bits/stdc++.h>
using namespace std;
#define INF 0x3f3f3f3f
const int maxn = 1e5+7;
long long jie[20];
long long a[maxn];
int M,N;
void get_jie()
{
jie[0]=jie[1]=1;
for(int i=2; i<20; ++i)
jie[i]=1LL*i*jie[i-1];
}
long long ans;
long long cal()
{
long long di=1;
for(int i=1; i<=M; ++i)
{
di*=(jie[ a[i]-a[i-1] ]);
}
return jie[ a[M] ]/di;
}
void dfs(int deep,int n, int m, int s)
{
if(m==0)
{
ans+=cal();
return ;
}
for(int i=s; i<=n; ++i)
{
a[deep]=i;
dfs(deep+1,n,m-1,i);
}
}
int main()
{
int n,m;
get_jie();
for(n=1; n<=5; ++n)
{
cout<<"n="<<n<<" ";
for(m=2; m<=5; ++m)
{
N=n,M=m;
ans=0;
dfs(1,n,m,0);
cout<<ans<<" ";
}
cout<<endl;
}
/*
cin>>n>>m;
N=n,M=m;
ans=0;
dfs(1,n,m,0);
cout<<ans<<endl;*/
return 0;
}
/*
*/
题意:推公式
题解:打表找规律
CODE:
#include <bits/stdc++.h> using namespace std; const int mod = 1000000007; long long inv(long long a) { if(a==1)return 1; return inv(mod%a)*(mod-mod/a)%mod; } long long quick_pow(long long a, long long n) { long long ans=1; while(n) { if(n&1)ans=(ans*a)%mod; a=(a*a)%mod; n>>=1; } return ans; } int main() { long long n,m; int T; long long ans; cin>>T; while(T--) { cin>>n>>m; ans=(quick_pow(m,n+1)-1)*inv(m-1)%mod; cout<<ans<<endl; } return 0; }
找规律代码QAQ:
#include <bits/stdc++.h>
using namespace std;
#define INF 0x3f3f3f3f
const int maxn = 1e5+7;
long long jie[20];
long long a[maxn];
int M,N;
void get_jie()
{
jie[0]=jie[1]=1;
for(int i=2; i<20; ++i)
jie[i]=1LL*i*jie[i-1];
}
long long ans;
long long cal()
{
long long di=1;
for(int i=1; i<=M; ++i)
{
di*=(jie[ a[i]-a[i-1] ]);
}
return jie[ a[M] ]/di;
}
void dfs(int deep,int n, int m, int s)
{
if(m==0)
{
ans+=cal();
return ;
}
for(int i=s; i<=n; ++i)
{
a[deep]=i;
dfs(deep+1,n,m-1,i);
}
}
int main()
{
int n,m;
get_jie();
for(n=1; n<=5; ++n)
{
cout<<"n="<<n<<" ";
for(m=2; m<=5; ++m)
{
N=n,M=m;
ans=0;
dfs(1,n,m,0);
cout<<ans<<" ";
}
cout<<endl;
}
/*
cin>>n>>m;
N=n,M=m;
ans=0;
dfs(1,n,m,0);
cout<<ans<<endl;*/
return 0;
}
/*
*/
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