给定一个数字n,任务是找到奇数因子和。 例如:
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Input : n = 30Output : 24Odd dividers sum 1 + 3 + 5 + 15 = 24 Input : 18Output : 13Odd dividers sum 1 + 3 + 9 = 13
让p 1. P 2. ,…p K 是 主要因素 让我们 1. A. 2. , .. A. K 是p的最高权力 1. P 2. , .. P K 分别除以n,也就是说,我们可以把n写成 n=(p 1. A. 1. )*(p 2. A. 2. )*…(p K A. K ) .
Sum of divisors = (1 + p1 + p12 ... p1a1) * (1 + p2 + p22 ... p2a2) * ............................................. (1 + pk + pk2 ... pkak)
为了求奇数因子之和,我们只需要忽略偶数因子及其幂。例如,考虑n=18。它可以写成2 1. 3. 2. 所有因素中的太阳是(1)*(1+2)*(1+3+3) 2. ).奇数因子之和(1)*(1+3+3) 2. ) = 13. 为了去除所有偶数因子,我们反复地将n除以2。在这一步之后,我们只得到奇数因子。请注意,2是唯一的偶数素数。
C++
// Formula based Java program // to find sum of all divisors // of n. #include <iostream> #include <cmath> using namespace std; // Returns sum of all // factors of n. int sumofoddFactors( int n) { // Traversing through // all prime factors. int res = 1; // ignore even factors by // removing all powers // of 2 while (n % 2 == 0) n = n / 2; for ( int i = 3; i <= sqrt (n); i++) { // While i divides n, // print i and divide n int count = 0, curr_sum = 1; int curr_term = 1; while (n % i == 0) { count++; n = n / i; curr_term *= i; curr_sum += curr_term; } res *= curr_sum; } // This condition is to handle // the case when n is a // prime number. if (n >= 2) res *= (1 + n); return res; } // Driver code int main() { int n = 30; cout << sumofoddFactors(n); return 0; } // This code is contributed by // Manish Shaw(manishshaw1) |
JAVA
// Formula based Java program // to find sum of all divisors // of n. import java.io.*; import java.math.*; class GFG { // Returns sum of all // factors of n. static int sumofoddFactors( int n) { // Traversing through // all prime factors. int res = 1 ; // ignore even factors by // removing all powers // of 2 while (n % 2 == 0 ) n = n / 2 ; for ( int i = 3 ; i <= Math.sqrt(n); i++) { // While i divides n, print i // and divide n int count = 0 , curr_sum = 1 ; int curr_term = 1 ; while (n % i == 0 ) { count++; n = n / i; curr_term *= i; curr_sum += curr_term; } res *= curr_sum; } // This condition is to handle // the case when n is a // prime number. if (n >= 2 ) res *= ( 1 + n); return res; } // Driver code public static void main(String args[]) throws IOException { int n = 30 ; System.out.println(sumofoddFactors(n)); } } /* This code is contributed by Nikita Tiwari.*/ |
Python3
# Formula based Python program # to find sum of all divisors # of n. import math # Returns sum of all # factors of n. def sumofoddFactors(n) : # Traversing through # all prime factors. res = 1 # ignore even factors by # removing all powers # of 2 while (n % 2 = = 0 ) : n = int (n / 2 ) for i in range ( 3 , int (math.sqrt(n)) + 1 ) : # While i divides n, # pri and divide n count = 0 curr_sum = 1 curr_term = 1 while (n % i = = 0 ) : count = count + 1 n = int (n / i) curr_term * = i curr_sum = curr_sum + curr_term res = res * curr_sum # This condition is to # handle the case when # n is a prime number. if (n > = 2 ) : res = res * ( 1 + n) return res # Driver code n = 30 print (sumofoddFactors(n)) # This code is contributed by # Manish Shaw(manishshaw1) |
C#
// Formula based C# program to find sum // of all divisors of n. using System; class GFG { // Returns sum of all factors of n. static int sumofoddFactors( int n) { // Traversing through // all prime factors. int res = 1; // ignore even factors by // removing all powers // of 2 while (n % 2 == 0) n = n / 2; for ( int i = 3; i <= Math.Sqrt(n); i++) { // While i divides n, print i // and divide n int count = 0, curr_sum = 1; int curr_term = 1; while (n % i == 0) { count++; n = n / i; curr_term *= i; curr_sum += curr_term; } res *= curr_sum; } // This condition is to handle // the case when n is a // prime number. if (n >= 2) res *= (1 + n); return res; } // Driver code public static void Main() { int n = 30; Console.Write(sumofoddFactors(n)); } } // This code is contributed by nitin mittal. |
PHP
<?php // Formula based PHP program // to find sum of all divisors // of n. // Returns sum of all // factors of n. function sumofoddFactors( $n ) { // Traversing through // all prime factors. $res = 1; // ignore even factors by // removing all powers // of 2 while ( $n % 2 == 0) $n = intval ( $n / 2); for ( $i = 3; $i <= sqrt( $n ); $i ++) { // While i divides n, // pr$i and divide n $count = 0; $curr_sum = 1; $curr_term = 1; while ( $n % $i == 0) { $count ++; $n = intval ( $n / $i ); $curr_term *= $i ; $curr_sum += $curr_term ; } $res *= $curr_sum ; } // This condition is to // handle the case when // n is a prime number. if ( $n >= 2) $res *= (1 + $n ); return $res ; } // Driver code $n = 30; echo (sumofoddFactors( $n )); // This code is contributed by // Manish Shaw(manishshaw1) ?> |
Javascript
<script> // Formula based Javascript program // to find sum of all divisors // of n. // Returns sum of all // factors of n. function sumofoddFactors(n) { // Traversing through // all prime factors. let res = 1; // ignore even factors by // removing all powers // of 2 while (n % 2 == 0) n = n / 2; for (let i = 3; i <= n; i++) { // While i divides n, // print i and divide n let count = 0, curr_sum = 1; let curr_term = 1; while (n % i == 0) { count++; n = n / i; curr_term *= i; curr_sum += curr_term; } res *= curr_sum; } // This condition is to handle // the case when n is a // prime number. if (n >= 2) res *= (1 + n); return res; } let n = 30; document.write(sumofoddFactors(n)); </script> |
输出:
24
请参阅完整的文章 求一个数的奇数因子之和 更多细节!
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