ACM-ICPC 2018 焦作賽區網路預賽G Give Candies
阿新 • • 發佈:2018-12-10
題意:給你n個東西,叫你把n分成任意段,這樣的分法有幾種。
分析:(HDU 4704原題)隔板法,ans=C(1,n-1)+C(2,n-1)+...+C(n-1,n-1)=2^(n-1)。需要用到尤拉降冪公式,參考開啟,證明需要用到尤拉定理,a^(φ(m))同餘1(mod m) (a與m互質)。
程式碼:
#pragma GCC optimize(2) #pragma GCC optimize(3) #pragma GCC optimize(4) #pragma comment(linker, "/STACK:102400000,102400000") #include<unordered_map> #include<unordered_set> #include<algorithm> #include<iostream> #include<fstream> #include<complex> #include<cstdlib> #include<cstring> #include<cassert> #include<iomanip> #include<string> #include<cstdio> #include<bitset> #include<vector> #include<cctype> #include<cmath> #include<ctime> #include<stack> #include<queue> #include<deque> #include<list> #include<set> #include<map> using namespace std; #define pt(a) cout<<a<<endl #define debug test #define mst(ss,b) memset((ss),(b),sizeof(ss)) #define rep(i,a,n) for (int i=a;i<=n;i++) #define per(i,a,n) for (int i=n-1;i>=a;i--) #define all(x) (x).begin(),(x).end() #define fi first #define se second #define SZ(x) ((int)(x).size()) #define ll long long #define ull unsigned long long #define pb push_back #define mp make_pair #define inf 0x3f3f3f3f #define eps 1e-10 #define PI acos(-1.0) typedef pair<int,int> PII; const ll mod = 1e9+7; const int N = 1e6+10; ll gcd(ll p,ll q){return q==0?p:gcd(q,p%q);} ll qp(ll a,ll b) {ll res=1;a%=mod; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;} int to[4][2]={{-1,0},{1,0},{0,-1},{0,1}}; int t; string s; int main() { ios::sync_with_stdio(0),cin.tie(0),cout.tie(0); cin>>t; while(t--) { cin>>s; int l=s.size(); ll res=0,phi=mod-1; rep(i,0,l-1) res=(res*10+s[i]-'0')%phi; cout<<qp(2,res-1+phi)<<endl; } return 0; }