POJ 2407-relatives (Euler function value for an integer)

RelativesTime limit:MS Memory Limit:65536KB 64bit IO Format:%i64d &%i64u SubmitStatusPracticePOJ 2407Appoint Description:System Crawler (2015-04-04)

Description

Given N, a positive integer, how many positive integers less than n is relatively prime to n? Integers A and B are relatively prime if there is no integers x > 1, y > 0, z > 0 such that a = XY and B = x Z.

Input

There is several test cases. For the test case, the standard input contains a line with n <= 1,000,000,000. A line containing 0 follows.

Output

For all test case there should is single line of output answering the question posed above.

Sample Input

7120

Sample Output

64

Test instructions: Give a number n, and the number of the N-ary is not greater than N.

#include <stdio.h> #include <math.h> #include <string.h> #include <stdlib.h> #include < iostream> #include <sstream> #include <algorithm> #include <set> #include <queue> #include <stack> #include <map>using namespace std;typedef long long ll;const int inf=0x3f3f3f3f;const double pi= ACOs ( -1.0); int Euler (int n) {    int m=floor (sqrt (n+0.5));    int ans=n;    for (int i=2;i<=m;i++) {        if (n%i==0) {            ans=ans/i* (i-1);            while (n%i==0) {                n/=i;}}    }    if (n>1)        ans=ans/n* (n-1);    return ans;} int main () {    int n;    while (~SCANF ("%d", &n)} {        if (!n) break;        printf ("%d\n", Euler (n));    }    return 0;}

POJ 2407-relatives (Euler function value for an integer)