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Java Exercises: Test if a given number is a perfect square or not

Java Basic: Exercise-197 with Solution

Write a Java program to test if a given number (positive integer ) is a perfect square or not.

Input number: 3 Output: 1 2 3 8 9 4 7 6 5

Pictorial Presentation:

Java Basic Exercises: Test if a given number is a perfect square or not

Sample Solution:

Java Code:

import java.util.*;
public class Solution {
 public static void main(String[] args) {
  Scanner in = new Scanner(System.in);
  System.out.print("Input a positive integer: ");
  int n = in .nextInt();
  System.out.print("Is the said number perfect square? " + is_Perfect_Square(n));
 }

 public static boolean is_Perfect_Square(int n) {
  int x = n % 10;
  if (x == 2 || x == 3 || x == 7 || x == 8) {
   return false;
  }
  for (int i = 0; i <= n / 2 + 1; i++) {
   if ((long) i * i == n) {
    return true;
   }
  }
  return false;
 }
}

Sample Output: 

Input a positive integer:  6
Is the said number perfect square? false

Flowchart:

Flowchart: Java exercises: Test if a given number is a perfect square or not

Java Code Editor:

Company:  LinkedIn

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Previous: Write a Java program to create a spiral array of n * n sizes from a given integer n.
Next: Write a Java program to get the position of a given prime number.

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Java: Tips of the Day

How to remove leading zeros from alphanumeric text?

Regex is the best tool for the job; what it should be depends on the problem specification. The following removes leading zeroes, but leaves one if necessary (i.e. it wouldn't just turn "0" to a blank string).

s.replaceFirst("^0+(?!$)", "")

The ^ anchor will make sure that the 0+ being matched is at the beginning of the input. The (?!$) negative lookahead ensures that not the entire string will be matched.

Test harness:

String[] in = {
    "01234",         // "[1234]"
    "0001234a",      // "[1234a]"
    "101234",        // "[101234]"
    "000002829839",  // "[2829839]"
    "0",             // "[0]"
    "0000000",       // "[0]"
    "0000009",       // "[9]"
    "000000z",       // "[z]"
    "000000.z",      // "[.z]"
};
for (String s : in) {
    System.out.println("[" + s.replaceFirst("^0+(?!$)", "") + "]");
}

Ref: https://bit.ly/2Qdcl8a