如果一个数的质因数只包括2、3和5，那么它被称为丑数。
也许某些数字具有仅有一个或两个因子的质因数，但这些因子必须是2、3和5之一。
In this article we will see how to check if a number is an Ugly number or not by using Java programming language.
To show you some instances
Instance-1
Input number is 20.
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让我们使用丑数的逻辑来检查一下。
Prime factors of 20 = 2, 2, 5
所以，正如你在这里注意到的，所有的质因数只包括2、3和5中的任意一个。
Hence, 20 is an ugly number.
Instance-2
Input number is 30.
让我们使用丑数的逻辑来检查一下。
Prime factors of 30 = 2, 3, 5
所以，正如你在这里注意到的，所有的质因数只包括2、3和5中的任意一个。
Hence, 30 is an ugly number.
Instance-3
Input number is 14.
让我们使用丑数的逻辑来检查一下。
Prime factors of 14 = 2, 7
So, as you notice here 7 is present at one of the prime factors above.
Hence, 14 is not an ugly number.
Algorithm
Step 1 − First we define a function for checking if the input number is a prime number or not.
步骤2 - 通过静态方法或用户定义的方法收集用户的输入。
步骤 3 − 初始化循环以找到输入数字的所有质因数。
第4步 - 找到质因数后，我们运行一个条件来检查因子是否只包含2、3和5。
Step 5 − If the condition is true then we are printing the input number is an ugly number otherwise the input number is not an ugly number.
Multiple Approaches
我们以不同的方法提供了解决方案。
通过使用静态输入值
By Using User Defined Method
让我们逐一查看Java程序及其输出。
Approach-1: By Using Static Input Value
In this approach one non−zero, positive integer value will be initialized in the program and then by using the algorithm we can check whether a number is an ugly number or not.
Example
import java.util.Scanner;
public class Main {
public static void main(String args[]) {
//declare a variable with a static value
int inputNumber = 25;
//declare a variable with boolean value
boolean check = true;
//initialise the loop for the checking of ugly number
for(int i = 2; i<=inputNumber; i++) {
// checks whether numbers only include 2,3 and 5
if(i!=2&&i!=3&&i!=5) {
// Checks if there are some other prime factors
if(inputNumber%i==0&&checkPrime(i)) {
// Sets the flag to false if there are some other prime factors
check = false;
break;
}
}
}
if(check) {
System.out.println(inputNumber+" is an ugly number");
} else {
System.out.println(inputNumber+" is Not an ugly number");
}
}
// Function that checks for prime
static boolean checkPrime(int number) {
boolean flag = true;
for(int i = 2; i<=number/2; i++) {
if(number%i==0) {
flag = false;
break;
}
}
return flag;
}
}
输出
25 is an ugly number
Approach-2: By Using User Defined Method
In this approach one non−zero, positive integer value will be initialized in the program and then we will call a user defined method by passing this input number as parameter.
在这个方法中，我们将使用算法来检查一个数字是否是一个丑数。
Example
import java.util.Scanner;
public class Main {
//initialise main method
public static void main(String[] args) {
//declare a variable with a static value
int inp = 56;
//check whether our condition is true or not in user defined method
//if true number is ugly otherwise not
if(checkUgly(inp)) {
System.out.println(inp+" is an ugly number");
} else {
System.out.println(inp+" is Not an ugly number");
}
}
// Function that checks for prime
static boolean checkPrime(int number) {
boolean flag = true;
for(int i = 2; i<=number/2; i++) {
if(number%i==0) {
flag = false;
break;
}
}
return flag;
}
//define the user defined method
//checking for ugly number
public static boolean checkUgly(int inputNumber) {
//declare a variable with boolean value
boolean check = true;
//initialise the loop for the checking of Ugly number
for(int i = 2; i<=inputNumber; i++) {
// checks whether numbers only include 2,3 and 5
if(i!=2&&i!=3&&i!=5) {
// Checks if there are some other prime factors
if(inputNumber%i==0&&checkPrime(i)) {
// Sets the flag to false if there are some other prime factors
return false;
}
}
}
return true;
}
}
输出
56 is Not an ugly number
In this article, we explored how to check a number whether it is an ugly number or not in Java by using different approaches.
