Submission #1609273

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Source Code Expand

#pragma region include
#include <iostream>
#include <iomanip>
#include <stdio.h>

#include <sstream>
#include <algorithm>
#include <iterator>
#include <cmath>
#include <complex>

#include <string>
#include <cstring>
#include <vector>
#include <tuple>
#include <bitset>

#include <queue>
#include <complex>
#include <set>
#include <map>
#include <stack>
#include <list>

#include <fstream>
#include <random>
//#include <time.h>
#include <ctime>
#pragma endregion //#include
/////////
#define REP(i, x, n) for(int i = x; i < n; ++i)
#define rep(i,n) REP(i,0,n)
#define ALL(X) X.begin(), X.end()
/////////
#pragma region typedef
typedef long long LL;
typedef long double LD;
typedef unsigned long long ULL;
typedef std::pair<LL,LL> PLL;//
typedef std::pair<int,int> PII;//
#pragma endregion //typedef
////定数
const int INF = (int)1e9;
const LL MOD = (LL)1e9+7;
const LL LINF = (LL)1e18+20;
const LD PI = acos(-1.0);
const double EPS = 1e-9;
/////////
using namespace::std;

void solve(){
	LL a,b,c;
	cin >> a >> b >> c;
	/*
	if(a<=1000 && c<=1000 ){
		vector< vector<LL> > dp(c+1,vector<LL>(a));
		dp[0][0] = 1;
		for(int i=1;i<a;++i){
			dp[0][i] = (dp[0][i-1]*b ) % MOD;
		}
		for(int j=1;j<=c;++j){
			dp[j][0] = 1;
		}
		for(int j=1;j<=c;++j){
			for(int i=1;i<a;++i){
				dp[j][i] = (dp[j-1][i]+dp[j][i-1]);
				if( dp[j][i] >= MOD ){
					dp[j][i] -= MOD;
				}
			}
		}

		cout << dp[c][a-1] << endl;
	}else
	*/
	if( a <= 100000 && c <= 100000 ){
		vector<LL> fact(100001);
		fact[0] = 1;
		for(LL i=1;i<=100000;++i){
			fact[i] = (fact[i-1]*i) % MOD;
		}
		/*
		k!の逆元は
		powMod(fact[k],MOD-2)で求める
		:フェルマーの小定理
		*/

		LL ans = 0;
		for(LL i=0;i<a;++i){
			//(c-1)+(a-i-1) C (c-1)
			LL n = (c-1)+(a-i-1);
			LL k = c-1;//固定値
			LL res = (fact[n]*powMod(fact[n-k],MOD-2)) % MOD;
			res = (res * powMod(fact[k],MOD-2) ) % MOD;
			res = (res * powMod(b,i) ) % MOD;
			ans += res;
			if( ans >= MOD ){
				ans -= MOD;
			}
		}
		cout << ans << endl;
	}
}

#pragma region main
signed main(void){
	std::cin.tie(0);
	std::ios::sync_with_stdio(false);
	std::cout << std::fixed;//小数を10進数表示
	cout << setprecision(16);//小数点以下の桁数を指定//coutとcerrで別	

	solve();
}
#pragma endregion //main()

Submission Info

Compile Error

./Main.cpp: In function ‘void solve()’:
./Main.cpp:93:44: error: ‘powMod’ was not declared in this scope
    LL res = (fact[n]*powMod(fact[n-k],MOD-2)) % MOD;
                                            ^