Bi-shoe and Phi-shoe
題目表述:
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.
輸入:
Input starts with an integer T (≤ 100), denoting the number of test cases.
Each case starts with a line containing an integer n (1 ≤ n ≤ 10000) denoting the number of students of Phi-shoe. The next line contains n space separated integers denoting the lucky numbers for the students. Each lucky number will lie in the range [1, 10的6次方]
輸出:
For each case, print the case number and the minimum possible money spent for buying the bamboos. See the samples for details.
樣例輸入:
3
5
1 2 3 4 5
6
10 11 12 13 14 15
2
1 1
樣例輸出:
Case 1: 22 Xukha
Case 2: 88 Xukha
Case 3: 4 Xukha
這個題的意思是給出幾個幸運數字,對於每一個幸運數字要求出一個N,並且N的尤拉函式的值不小於這個幸運數字,並且所有N的和要最小,所以每個N最小那麼N的和就是最小。對於每一個幸運數字,他的N的最小值就是大於幸運數字的第一個素數。在範圍內,把所有的素數都標記為0.
程式碼:
#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>
using namespace std;
#define maxn 1000010
int isprime[maxn];
void get_prime()//篩選素數,過程可以用筆寫一下,便於理解
{
int i,j;
memset(isprime,0,sizeof(isprime));
for(i=2;i<1001;i++)
{
if(isprime[i]==0)
{
for(j=i*i;j<maxn;j+=i)
{
isprime[j]=1;
}
}
}
}
int main()
{
int t,n;
int k;
int ans=1;
scanf("%d",&t);
get_prime();
while(t--)
{
long long sum=0;
scanf("%d",&n);
for(int i=0;i<n;i++)
{
scanf("%d",&k);
for(int j=k+1;j<=maxn;j++)
{
if(isprime[j]==0)
{
sum+=j;
break;
}
}
}
printf("Case %d: %lld Xukha\n",ans++,sum);
}
return 0;
}