Submission #19592

#	Time	Username	Problem	Language	Result	Execution time	Memory
19592		pjh0123	Σ (kriii4_P2)	C++98	100 / 100	7 ms	1256 KiB

P2

#include <stdio.h>
#include <string.h>
#include <vector>
#include <queue>
#include <stdlib.h>
#include <algorithm>
#include <cmath>
#define INFL 90000000000000000
#define PI 3.141592653589793238462643383279502884
#define SQ(a) ((a)*(a))
#define pb push_back
#define mod 1000000007
typedef long long ll;
typedef long double ld;
typedef double dd;
typedef std::pair<int,int> pii;
using namespace std;

ll m,n[11111],s[11111],inv,at,bt,a,b;
ll in(ll a){
	a%=mod;
	ll ret=1;
	ll x=mod-2;
	while(x){
		if(x%2){
			ret=ret*a%mod;			
		}
		a=a*a%mod;	
		x/=2;
	}
	return ret;
}
int main(){
	at=1;
	bt=1;
	scanf("%lld",&m);
	for(int i=0;i<m;i++){
		scanf("%lld%lld",&n[i],&s[i]);
		at=at*n[i]%mod;
		
	}
	a = in(at);
	b=0;
	for(int i=0;i<m;i++){
		inv=in(n[i]);
		b=(b+inv*at%mod*s[i]%mod)%mod;
	}
	
	printf("%lld",a*b%mod);
}

• Subtask 1: 100 / 100