Submission #2014308

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;

using ll=int64_t;
#define int ll

#define FOR(i,a,b) for(int i=int(a);i<int(b);i++)
#define REP(i,b) FOR(i,0,b)
#define MP make_pair
#define PB push_back
#define ALL(x) x.begin(),x.end()
#define REACH cerr<<"reached line "<<__LINE__<<endl
#define DMP(x) cerr<<"line "<<__LINE__<<" "<<#x<<":"<<x<<endl
#define ZERO(x) memset(x,0,sizeof(x))

using pi=pair<int,int>;
using vi=vector<int>;
using ld=long double;

template<class T,class U>
ostream& operator<<(ostream& os,const pair<T,U>& p){
	os<<"("<<p.first<<","<<p.second<<")";
	return os;
}

template<class T>
ostream& operator <<(ostream& os,const vector<T>& v){
	os<<"[";
	REP(i,(int)v.size()){
		if(i)os<<",";
		os<<v[i];
	}
	os<<"]";
	return os;
}

int read(){
	int i;
	scanf("%" SCNd64,&i);
	return i;
}

void printSpace(){
	printf(" ");
}

void printEoln(){
	printf("\n");
}

void print(int x,int suc=1){
	printf("%" PRId64,x);
	if(suc==1)
		printEoln();
	if(suc==2)
		printSpace();
}

string readString(){
	static char buf[3341000];
	scanf("%s",buf);
	return string(buf);
}

char* readCharArray(){
	static char buf[3341000];
	static int bufUsed=0;
	char* ret=buf+bufUsed;
	scanf("%s",ret);
	bufUsed+=strlen(ret)+1;
	return ret;
}

template<class T,class U>
void chmax(T& a,U b){
	if(a<b)
		a=b;
}

template<class T,class U>
void chmin(T& a,U b){
	if(a>b)
		a=b;
}

template<class T>
T Sq(const T& t){
	return t*t;
}

const int inf=LLONG_MAX/3;

const int mod=998244353;
template<class T,class U>
void add(T& a,U b){
	a=((ll)a+b)%mod;
}

template<class T,class U>
void sub(T& a,U b){
	a=((ll)a-b%mod+mod)%mod;
}

template<class T,class U>
void mult(T& a,U b){
	a=((ll)a*b)%mod;
}

ll modPow(ll a,ll p){
	ll s=1;
	REP(i,30){
		if((p>>i)&1)
			mult(s,a);
		mult(a,a);
	}
	return s;
}

ll modInv(ll a){
	return modPow(a,mod-2);
}

const int Vmax=1000010;
int fact[Vmax],factInv[Vmax];
void Init(){
	fact[0]=1;
	FOR(i,1,Vmax){
		fact[i]=fact[i-1];
		mult(fact[i],i);
	}
	factInv[Vmax-1]=modInv(fact[Vmax-1]);
	for(int i=Vmax-2;i>=0;i--){
		factInv[i]=factInv[i+1];
		mult(factInv[i],i+1);
	}
}
int Choose(int n,int k){
	return fact[n]*factInv[n-k]%mod*factInv[k]%mod;
}

signed main(){
	Init();
	int n=read(),m=read();
	int ans=0;
	{
		REP(i,n)if(i+2<=m){
			add(ans,Choose(i+2-1+i,i)*Choose(m-(i+2)+n-1-i,n-1-i)%mod*(i+2+i));
			if(i+1<=n-1)sub(ans,Choose(i+2+i,i)*Choose(m-(i+2)+n-1-i-1,n-1-i-1)%mod*(i+2+i+1));
		}
		if(m<=n)add(ans,Choose(m+n-1,n-1)*(m+n));
	}
	{
		REP(i,m)if(i+1<=n){
			add(ans,Choose(i+i+1-1,i+1-1)*Choose(m-1-i+n-(i+1),n-(i+1))%mod*(i+i+1));
			if(i+1<=m)sub(ans,Choose(i+i+1,i+1)*Choose(m-1-i-1+n-(i+1),n-(i+1))%mod*(i+i+1+1));
		}
		if(n<=m-1)add(ans,Choose(m-1+n,n)*(m+n));
	}
	mult(ans,modInv(Choose(m+n,n)));
	cout<<ans<<endl;
}

Submission Info

Compile Error

./Main.cpp: In function ‘ll read()’:
./Main.cpp:39:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%" SCNd64,&i);
                      ^
./Main.cpp: In function ‘std::string readString()’:
./Main.cpp:61:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%s",buf);
                 ^
./Main.cpp: In function ‘char* readCharArray()’:
./Main.cpp:69:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%s",ret);
                 ^

Judge Result