Submission #16698

#	Time	Username	Problem	Language	Result	Execution time	Memory
16698		gs14004	Xtreme gcd sum (kriii2_X)	C++14	1 / 4	4000 ms	17424 KiB

X

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <limits.h>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <algorithm>
#include <string>
#include <functional>
#include <vector>
#include <numeric>
#include <deque>
#include <utility>
#include <bitset>
#include <iostream>
using namespace std;
typedef long long lint;
typedef long double llf;
typedef pair<int, int> pi;
const int mod = 1e9 + 7;
const int rng = 1e6;

int che[1000005];
int moebius[1000005];
int n, a[10005], b[10005];
lint cnt[1000005];

lint get(int x){
	lint ret = 1;
	for(int i=0; i<n; i++){
		ret *= b[i] / x - (a[i] - 1) / x;
		ret %= mod;
	}
	return ret;
}

int main(){
	scanf("%d",&n);
	for(int i=0; i<n; i++){
		scanf("%d %d",&a[i], &b[i]);
	}
	for(int i=2; i<=1000000; i++){
		for(int j=i; j<=rng; j+=i){
			if(!che[j]) che[j] = i;
		}
	}
	for(int i=1; i<=rng; i++){
		int cnt = 0, lst = -1;
		int x = i;
		while(x > 1){
			if(lst == che[x]){
				cnt = -1;
				break;
			}
			lst = che[x];
			x /= lst;
			cnt++;
		}
		if(cnt < 0) continue;
		moebius[i] = cnt % 2 ? -1 : 1;
	}
	for(int i=1; i<=rng; i++){
		cnt[i] = get(i);
	}
	lint ret = 0;
	for(int i=1; i<=rng; i++){
		for(int j=1; i*j<=rng; j++){
			ret += 1ll * i * moebius[j] * cnt[i * j] % mod;
			ret %= mod;
		}
	}
	printf("%lld",ret);
}

• Subtask 1: 1 / 1
• Subtask 2: 0 / 3