The Euler functionTime Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 4389 Accepted Submission(s): 1821 Problem Description The Euler function phi is an important kind of function in number theory, (n) represents the amount of the numbers which are smaller than n and coprime to n, and this function has a lot of beautiful characteristics. Here comes a very easy question: suppose Input There are several test cases. Each line has two integers a, b (2<a<b<3000000). Output Output the result of (a)+ (a+1)+....+ (b) Sample Input 3 100 Sample Output 3042 Source 2009 Multi-University Training Contest 1 - Host Recommend gaojie | We have carefully selected several similar problems for you: 2818 2825 2822 2821 2820 |
打表求欧拉函数值
注意数组开成long long 型
第一种：稍微快一点
#include <stdio.h>
#include <math.h>
#include <vector>
#include <queue>
#include <string>
#include <string.h>
#include <stdlib.h>
#include <iostream>
#include <algorithm>
#define maxn 3000000+100
using namespace std;
long long E[maxn];
void euler()
{
E[1]=1;
for(int i=2;i<maxn;i++)
E[i]=i;
for(int i=2;i<maxn;i++){
if(E[i]==i)
for(int j=i;j<maxn;j+=i){
E[j]=E[j]/i*(i-1);
}
}
for(int i=2;i<maxn;i++)
E[i]+=E[i-1];
}
int main()
{
euler();
int a,b;
while(scanf("%d%d",&a,&b)!=EOF)
printf("%lld\n",E[b]-E[a-1]);
return 0;
}
第二种
#include <stdio.h>
#include <math.h>
#include <vector>
#include <queue>
#include <string>
#include <string.h>
#include <stdlib.h>
#include <iostream>
#include <algorithm>
#define maxn 3000000+100
using namespace std;
long long E[maxn];
void euler()
{
for(int i=2;i<maxn;i++){
if(!E[i])
for(int j=i;j<maxn;j+=i){
if(!E[j])E[j]=j;
E[j]=E[j]/i*(i-1);
}
E[i]+=E[i-1];
}
}
int main()
{
euler();
int a,b;
while(scanf("%d%d",&a,&b)!=EOF)
printf("%lld\n",E[b]-E[a-1]);
return 0;
}
版权声明：本文为博主原创文章，转载请注明出处。