Create GCDEX - GCD Extreme

Author: fuad7161

Euler's totient function/GCDEX - GCD Extreme

@@ -0,0 +1,144 @@
+//Author: Fuadul Hasan([email protected])
+//BSMRSTU,Gopalganj
+//#include<bits/stdc++.h>
+#define _USE_MATH_DEFINES
+#include <set>
+#include <map>
+#include <list>
+#include <queue>
+#include <stack>
+#include <cmath>
+#include <ctime>
+#include <cstdio>
+#include <string>
+#include <vector>
+#include <bitset>
+#include <random>
+#include <cassert>
+#include <cstring>
+#include <sstream>
+#include <complex>
+#include <numeric>
+#include <iostream>
+#include <algorithm>
+#include <functional>
+#include <unordered_set>
+#include <unordered_map>
+using namespace std;
+
+//debug..........
+#define error(args...) {vector<string>_v=split(#args,',');err(_v.begin(),args);cout<<endl;}
+vector<string> split(const string &s, char c) {vector<string>v; stringstream ss(s); string x;while (getline(ss, x, c))v.emplace_back(x); return move(v);} void err(vector<string>::iterator it) {}
+template<typename T, typename... Args>void err(vector<string>::iterator it, T a, Args...args) {cout << it->substr((*it)[0] == ' ', it->length()) << " = " << a << " "; err(++it, args...);}
+
+//............ignore it..................//
+#define F first
+#define S second
+
+#define Pi atan(1)*4
+#define mp make_pair
+#define pb  push_back
+const int M	= 1e9 + 7;
+
+#define ld  long double
+#define ll  long long int
+#define happy cin.tie(0);
+
+#define point(x) cout<<fixed<<setprecision(x)
+int length(string s){return (int)s.size();}
+
+#define mem(a)  memset(a , 0 ,sizeof a)
+#define memn(a) memset(a , -1 ,sizeof a)
+
+#define coding ios::sync_with_stdio(false);
+#define Unique(c) (c).resize(unique(all(c))-(c).begin())
+#define vout(v) for (auto z: v) cout << z << " "; cout << endl;
+
+int length(long long x){int l = 0;for(long long i=x;i;i/=10)l++;return l;}
+int dx[8]= {1,0,-1,0,-1,-1,1,1};
+int dy[8]= {0,1,0,-1,-1,1,-1,1}; 
+
+
+#define rep(i,b,e)  for(__typeof(e) i = (b) ; i != (e + 1) - 2 * ((b) > (e))  ; i += 1 - 2 * ((b) > (e)))
+
+long long power(long long a,long long n){ll res = 1;while(n){if(n&1) res = ((res%M)*(a%M))%M;a = ((a%M)*(a%M))%M;n>>=1;}return res%M;}
+
+#define Test cout<<"Case #"<<tc++<<": ";
+int tc = 1;
+
+inline void read(std::vector<int> &v){for(int i=0;i<(int)v.size();i++){cin>>(v[i]);}}
+inline void readl(std::vector<ll> &v){for(int i=0;i<(int)v.size();i++){cin>>(v[i]);}}
+
+template<class T> bool remin(T& a, const T& b) { return a > b ? a = b, 1 : 0; }
+template<class T> bool remax(T& a, const T& b) { return a < b ? a = b, 1 : 0; }
+
+inline void read(int v[],int n){for(int i=0;i<n;i++){cin>>(v[i]);}}
+inline void readl(ll v[],int n){for(int i=0;i<n;i++){cin>>(v[i]);}}
+
+inline int add(int a, int b, int mod) {a += b ; return a >= mod ? a - mod : a ;}
+inline int sub(int a, int b, int mod) {a -= b ; return a < 0 ? a + mod : a ;}
+inline int mul(int a, int b, int mod) {return (ll)a * b % mod ;}
+
+#define   pr 	pair<int, int> 
+#define   vpr 	vector<pr> 
+#define   vi   	std::vector<int>
+#define   vll  	std::vector<ll>
+#define   all(n) n.begin(),n.end()
+
+
+const int Inf           = (int)2e9 + 5;
+const ll  Lnf           = (ll)2e18 + 5;
+const int N             = 5e5 + 5;
+const int NN            = 1e6 + 5;
+
+int phi[NN+10];
+ll res[NN+10];
+
+void pre_calculation(){
+	phi[1] = 1;
+	for(int i=2;i<=NN;i++){
+		if(phi[i] == 0){
+			phi[i] = i-1;
+			for(int j=i+i;j<=NN;j+=i){
+				if(phi[j] == 0)phi[j] = j;
+				phi[j] = phi[j] - phi[j]/i;
+			}
+		}
+	}
+	for(int i=1;i<=NN;i++){
+		for(int j=i+i; j<=NN;j+=i){
+			res[j]+= (ll)(i*phi[j/i]);
+		}
+	}
+
+	for(int i=1;i<NN;i++){
+		res[i] += res[i-1];
+	}
+}
+
+int solve() 
+{
+	
+	//Test
+
+	pre_calculation();
+	int n;
+	while(cin>>n, n){
+		cout<<res[n]<<endl;
+	}
+
+
+
+	return 0;
+	//error();
+}
+int main(){
+
+	happy coding
+	int test = 1;
+	//cin>>test;
+	while (test--)solve();return 0;
+}
+
+
+