How to create pyramid of numbers in Java?
How to create Pyramid of Number Patterns in Java?
This is one of the frequently asked java interview question for freshers. This question tests the candidate’s logical ability as well as the basic understanding of Java language. They can ask you to create pyramid of numbers with different patterns like in the below image:
In this chapter, we will try to write the java programs to create pyramid of numbers in all different patterns one by one.
Write java program to create pyramid of numbers like in Pattern 1 of the given image?
Take the input from the user and assign it to noOfRows. This will be the number of rows he wants in a pyramid.
Define one variable called rowCount and initialize it to 1. This will hold the value of current row count.
At the beginning of each row, we print ‘i’ spaces where ‘i’ will be value from noOfRows to 1. At the end of each row, we print rowCount value rowCount times. i.e in the first row, 1 will be printed once. In the second row, 2 will be printed twice and so on.
Below is the java code which implements this logic.
Write the code for binary search algorithm as follows:
package com.javabykiran.patterns;
import java.util.Scanner;
public class JbkPyramidPattern1 {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
// Taking noOfRows value from the user
System.out.println("How Many Rows You Want In Your Pyramid?");
int noOfRows = sc.nextInt();
// Initializing rowCount with 1
int rowCount = 1;
System.out.println("Here Is Your Pyramid");
// Implementing the logic
for (int i = noOfRows; i > 0; i--) {
// Printing i spaces at the beginning of each row
for (int j = 1; j <= i; j++) {
System.out.print(" ");
}
// Printing 'rowCount' value 'rowCount' times at the end of each row
for (int j = 1; j <= rowCount; j++) {
System.out.print(rowCount + " ");
}
System.out.println();
// Incrementing the rowCount
rowCount++;
}
}
}
Output:
How Many Rows You Want In Your Pyramid?
9
Here Is Your Pyramid
1
2 2
3 3 3
4 4 4 4
5 5 5 5 5
6 6 6 6 6 6
7 7 7 7 7 7 7
8 8 8 8 8 8 8 8
9 9 9 9 9 9 9 9 9
How to create pyramid of numbers in Java like in Pattern 2 of the given image?
In this pattern also, we use same logic but instead of printing rowCount value rowCount times at the end of each row, we print ‘j’ where j value will be from 1 to rowCount.
package com.javabykiran.patterns;
import java.util.Scanner;
public class JbkPyramidPattern2 {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
// Taking noOfRows value from the user
System.out.println("How Many Rows You Want In Your Pyramid?");
int noOfRows = sc.nextInt();
// Initializing rowCount with 1
int rowCount = 1;
System.out.println("Here Is Your Pyramid");
// Implementing the logic
for (int i = noOfRows; i > 0; i--) {
// Printing i spaces at the beginning of each row
for (int j = 1; j <= i; j++) {
System.out.print(" ");
}
// Printing 'j' value at the end of each row
for (int j = 1; j <= rowCount; j++) {
System.out.print(j + " ");
}
System.out.println();
// Incrementing the rowCount
rowCount++;
}
}
}
Output:
How Many Rows You Want In Your Pyramid?
9
Here Is Your Pyramid
1
1 2
1 2 3
1 2 3 4
1 2 3 4 5
1 2 3 4 5 6
1 2 3 4 5 6 7
1 2 3 4 5 6 7 8
1 2 3 4 5 6 7 8 9
Write a java program to create pyramid of stars(*) like in the Pattern 3 of the given image?
The same logic is used here also. But, instead of printing rowCount or j value at the end of each row, we print star(*).
package com.javabykiran.patterns;
import java.util.Scanner;
public class JbkPyramidPattern3 {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
// Taking noOfRows value from the user
System.out.println("How Many Rows You Want In Your Pyramid?");
int noOfRows = sc.nextInt();
// Initializing rowCount with 1
int rowCount = 1;
System.out.println("Here Is Your Pyramid");
// Implementing the logic
for (int i = noOfRows; i > 0; i--) {
// Printing i spaces at the beginning of each row
for (int j = 1; j <= i; j++) {
System.out.print(" ");
}
// Printing * at the end of each row
for (int j = 1; j <= rowCount; j++) {
System.out.print("*");
}
System.out.println();
// Incrementing the rowCount
rowCount++;
}
}
}
Output:
How Many Rows You Want In Your Pyramid?
9
Here Is Your Pyramid
*
* *
* * *
* * * *
* * * * *
* * * * * *
* * * * * * *
* * * * * * * *
* * * * * * * * *
Write java program to print pyramid of numbers like in the Pattern 4 of the given image?
In this problem, we print i*2 spaces at the beginning of each row instead of just i spaces. At the end of each row, we print ‘j’ where j value will be from 1 to rowCount and from rowCount-1 to 1.
package com.javabykiran.patterns;
import java.util.Scanner;
public class JbkPyramidPattern4 {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
// Taking noOfRows value from the user
System.out.println("How Many Rows You Want In Your Pyramid?");
int noOfRows = sc.nextInt();
// Initializing rowCount with 1
int rowCount = 1;
System.out.println("Here Is Your Pyramid");
// Implementing the logic
for (int i = noOfRows; i > 0; i--) {
// Printing i*2 spaces at the beginning of each row
for (int j = 1; j <= i * 2; j++) {
System.out.print(" ");
}
// Printing j value where j value will be from 1 to rowCount
for (int j = 1; j <= rowCount; j++) {
System.out.print(j + " ");
}
// Printing j value where j value will be from rowCount-1 to 1
for (int j = rowCount - 1; j >= 1; j--) {
System.out.print(j + " ");
}
System.out.println();
// Incrementing the rowCount
rowCount++;
}
}
}
Output:
How Many Rows You Want In Your Pyramid?
9
Here Is Your Pyramid
1
1 2 1
1 2 3 2 1
1 2 3 4 3 2 1
1 2 3 4 5 4 3 2 1
1 2 3 4 5 6 5 4 3 2 1
1 2 3 4 5 6 7 6 5 4 3 2 1
1 2 3 4 5 6 7 8 7 6 5 4 3 2 1
1 2 3 4 5 6 7 8 9 8 7 6 5 4 3 2 1
Write Java program to print reverse pyramid of numbers like in the Pattern 5 of the given image?
In this problem, we iterate outer loop in the reverse order i.e from 1 to noOfRows and initialize the rowCount to noOfRows.
package com.javabykiran.patterns;
import java.util.Scanner;
public class JbkPyramidPattern5 {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
// Taking noOfRows value from the user
System.out.println("How Many Rows You Want In Your Pyramid?");
int noOfRows = sc.nextInt();
// Initializing rowCount with noOfRows
int rowCount = noOfRows;
System.out.println("Here Is Your Pyramid");
// Implementing the logic
for (int i = 0; i < noOfRows; i++) {
// Printing i*2 spaces at the beginning of each row
for (int j = 1; j <= i * 2; j++) {
System.out.print(" ");
}
// Printing j where j value will be from 1 to rowCount
for (int j = 1; j <= rowCount; j++) {
System.out.print(j + " ");
}
// Printing j where j value will be from rowCount-1 to 1
for (int j = rowCount - 1; j >= 1; j--) {
System.out.print(j + " ");
}
System.out.println();
// Decrementing the rowCount
rowCount--;
}
}
}
Output:
How Many Rows You Want In Your Pyramid?
9
Here Is Your Pyramid
1 2 3 4 5 6 7 8 9 8 7 6 5 4 3 2 1
1 2 3 4 5 6 7 8 7 6 5 4 3 2 1
1 2 3 4 5 6 7 6 5 4 3 2 1
1 2 3 4 5 6 5 4 3 2 1
1 2 3 4 5 4 3 2 1
1 2 3 4 3 2 1
1 2 3 2 1
1 2 1
1
How do you create pyramid of numbers like in the Pattern 6 of the given image?
In this problem, at the end of each row we print ‘j’ where ‘j’ value will be from i to noOfRows and from noOfRows-1 to i.
package com.javabykiran.patterns;
import java.util.Scanner;
public class JbkPyramidPattern6 {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
// Taking noOfRows value from the user
System.out.println("How Many Rows You Want In Your Pyramid?");
int noOfRows = sc.nextInt();
// Initializing rowCount with 1
int rowCount = 1;
System.out.println("Here Is Your Pyramid");
// Implementing the logic
for (int i = noOfRows; i >= 1; i--) {
// Printing i*2 spaces at the beginning of each row
for (int j = 1; j <= i * 2; j++) {
System.out.print(" ");
}
// Printing j where j value will be from i to noOfRows
for (int j = i; j <= noOfRows; j++) {
System.out.print(j + " ");
}
// Printing j where j value will be from noOfRows-1 to i
for (int j = noOfRows - 1; j >= i; j--) {
System.out.print(j + " ");
}
System.out.println();
// Incrementing the rowCount
rowCount++;
}
}
}
Output:
How Many Rows You Want In Your Pyramid?
9
Here Is Your Pyramid
9
8 9 8
7 8 9 8 7
6 7 8 9 8 7 6
5 6 7 8 9 8 7 6 5
4 5 6 7 8 9 8 7 6 5 4
3 4 5 6 7 8 9 8 7 6 5 4 3
2 3 4 5 6 7 8 9 8 7 6 5 4 3 2
1 2 3 4 5 6 7 8 9 8 7 6 5 4 3 2 1