The Euler function[hdu2824]

Source: Internet
Author: User

The Euler function
Time limit:2000/1000 MS (java/others) Memory limit:32768/32768 K (java/others)
Total submission (s): 6018 Accepted Submission (s): 2539


Problem Description
The Euler function phi is an important kind of function in number theory, (n) represents the amount of the numbers which a Re smaller than N and coprime to n, and this function have a lot of beautiful characteristics. Here comes a very easy question:suppose is given a, B, try to calculate (a) + (a+1) +....+ (b)

Input
There is several test cases. Each line has a integers a, b (2<a<b<3000000).

Output
Output The result of (a) + (a+1) +....+ (b)

Sample Input
3 100

Sample Output
3042

3000000 of the data range, did not expect to be directly added ... Contribute one MLE.

#include <stdio.h>#include<string.h>inteuler[3000010];voidEuler_sieve_method (int* Euler,intN) {euler[1] =1;  for(inti =2; I < n; i++) {Euler[i]=i; }     for(inti =2; I < n; i++) {        if(Euler[i] = =i) { for(intj = i; J < N; J + =i) {euler[j]= Euler[j]/I * (i-1); }        }    }}intMain () {Euler_sieve_method (Euler,3000005); intA, B;  while(SCANF ("%d%d", &a, &b)! =EOF) {__int64 s=0;  for(inti = A; I <= b; i++) {s+=Euler[i]; } printf ("%i64d\n", s); }    return 0;}
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The Euler function[hdu2824]

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