LightOJ - 1370 - Bi-shoe and Phi-shoe(欧拉函数)
作者:互联网
链接:
https://vjudge.net/problem/LightOJ-1370
题意:
Bamboo Pole-vault is a massively popular sport in Xzhiland. And Master Phi-shoe is a very popular coach for his success. He needs some bamboos for his students, so he asked his assistant Bi-Shoe to go to the market and buy them. Plenty of Bamboos of all possible integer lengths (yes!) are available in the market. According to Xzhila tradition,
Score of a bamboo = Φ (bamboo's length)
(Xzhilans are really fond of number theory). For your information, Φ (n) = numbers less than n which are relatively prime (having no common divisor other than 1) to n. So, score of a bamboo of length 9 is 6 as 1, 2, 4, 5, 7, 8 are relatively prime to 9.
The assistant Bi-shoe has to buy one bamboo for each student. As a twist, each pole-vault student of Phi-shoe has a lucky number. Bi-shoe wants to buy bamboos such that each of them gets a bamboo with a score greater than or equal to his/her lucky number. Bi-shoe wants to minimize the total amount of money spent for buying the bamboos. One unit of bamboo costs 1 Xukha. Help him.
思路:
欧拉函数打表,从小到大挨个尝试花费。
代码:
#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<algorithm>
#include<math.h>
#include<vector>
#include<map>
using namespace std;
typedef long long LL;
const int INF = 1e9;
const int MAXN = 1e6+10;
const int MOD = 1e9+7;
struct Phi
{
int v, p;
}phi[MAXN];
int prime[MAXN];
int Cost[MAXN], a[MAXN];
int tot, n;
void Euler()
{
tot = 0;
for (int i = 1;i < MAXN;i++)
phi[i].v = i, phi[i].p = 0;
phi[1].p = 1;
for (int i = 2;i < MAXN;i++)
{
if (!phi[i].p)
{
phi[i].p = i-1;
prime[tot++] = i;
}
for (int j = 0;j < tot && 1LL*i*prime[j] < MAXN;j++)
{
if (i%prime[j])
phi[i*prime[j]].p = phi[i].p*(prime[j]-1);
else
{
phi[i*prime[j]].p = phi[i].p*prime[j];
break;
}
}
}
}
bool cmp(Phi a, Phi b)
{
if (a.p != b.p)
return a.p < b.p;
return a.v < b.v;
}
int main()
{
Euler();
/*
sort(phi+1, phi+MAXN, cmp);
int pos = 2;
for (int i = 1;i < MAXN;i++)
{
while(phi[pos].p < i)
pos++;
Cost[i] = phi[pos].v;
}
*/
int t, cnt = 0;
scanf("%d", &t);
while(t--)
{
printf("Case %d:", ++cnt);
scanf("%d", &n);
for (int i = 1;i <= n;i++)
scanf("%d", &a[i]);
sort(a+1, a+1+n);
LL sum = 0;
for (int i = 2, j = 1;i < MAXN && j <= n;i++)
{
while(phi[i].p >= a[j] && j <= n)
sum += i, j++;
}
printf(" %lld Xukha\n", sum);
}
return 0;
}
标签:prime,Phi,int,LightOJ,phi,MAXN,shoe,include 来源: https://www.cnblogs.com/YDDDD/p/11846242.html