caioj 1158 欧拉函数

直接套模板，这道题貌似单独求还快一些

解法一

#include<cstdio>
#include<cctype>
#define REP(i, a, b) for(int i = (a); i < (b); i++)
#define _for(i, a, b) for(int i = (a); i <= (b); i++)
using namespace std;

typedef long long ll;
const int MAXN = 21234567;
int euler[MAXN];

void get_euler()
{
	_for(i, 1, MAXN) euler[i] = i;
	_for(i, 2, MAXN)
		if(euler[i] == i)
			for(int j = i; j <= MAXN; j += i)
				euler[j] = euler[j] / i * (i - 1);
}

void read(ll& x)
{
	int f = 1; x = 0; char ch = getchar();
	while(!isdigit(ch)) { if(ch == '-') f = -1; ch = getchar(); }
	while(isdigit(ch)) { x = x * 10 + ch - '0'; ch = getchar(); }
	x *= f;
}

int main()
{
	get_euler();
	ll n, x; read(n);
	while(n--)
	{
		read(x);
		printf("%lld\n", euler[x]);
	}
	return 0;
}

解法二

#include<cstdio>
#include<cctype>
#define REP(i, a, b) for(int i = (a); i < (b); i++)
#define _for(i, a, b) for(int i = (a); i <= (b); i++)
using namespace std;

typedef long long ll;
const int MAXN = 21234567;

ll euler(ll x)
{
	ll ret = x;
	for(int i = 2; i * i <= x; i++)
		if(x % i == 0)
		{
			ret = ret / i * (i - 1);
			while(x % i == 0) x /= i;
			if(x == 1) break;
		}
	if(x > 1) ret = ret / x * (x - 1);
	return ret;
}

void read(ll& x)
{
	int f = 1; x = 0; char ch = getchar();
	while(!isdigit(ch)) { if(ch == '-') f = -1; ch = getchar(); }
	while(isdigit(ch)) { x = x * 10 + ch - '0'; ch = getchar(); }
	x *= f;
}

int main()
{
	ll n, x; read(n);
	while(n--)
	{
		read(x);
		printf("%lld\n", euler(x));
	}
	return 0;
}