제출 #856126

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
856126		vjudge1	Savrsen (COCI17_savrsen)	C++17	0 / 120	329 ms	131072 KiB

savrsen

#include <bits/stdc++.h>
using namespace std;
#define sp << " " << 
#define int long long
#define vi vector<int>
#define pb push_back
#define F(xxx,yyy) for (int xxx=1;xxx<=yyy;xxx++)
#define pii pair<int,int>
#define all(x) x.begin()+1,x.end()
const int N = 1e7+1;

int d[N];
int sieve[N];


int expo(int x,int y) {
	if (!y) return 1;
	int e = expo(x,y/2);
	e*=e;
	if (y&1) e*=x;
	return e;
}

void solve() {	
	memset(sieve,0,sizeof sieve);
	for (int i=2;i<N;i++) {
		if (!sieve[i]) {
			sieve[i] = i;
			for (int j=i*i;j<N;j+=i)sieve[j] = i;
		}
	}
	d[1] = 1;
	for (int i=2;i<N;i++) {
		int p = sieve[i];
		int c = 0;
		int j = i;
		while (j%p == 0) j/=p,c++;
		d[i] = d[j]*(expo(p,c+1)-1)/(p-1);
	}
	int a,b;
	cin >> a >> b;
	int ans = 0;
	for (int i=a;i<=b;i++) ans+=abs(i-(d[i]-i));
	cout << ans << endl;
}     	
                 
                 
                 
                 
                 
                 
                 
                 
                                
signed main() { 
    ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    int t = 1;
    //cin >> t; 
    while (t --> 0) solve();
}

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