Welcome to Week 8 of our Java NPTEL course! This week, we dive into the world of advanced pyramid patterns and more. Let’s explore the solutions to these intriguing challenges while providing a brief explanation for each one.
Java Week 8: Q1 - Pyramid of Stars and Count
Question 1: Write a program that prints a pyramid of ’’ with a height ‘n’ and also prints the total number of ’’ characters in the pyramid.
import java.util.*;
public class Pattern1 {
public static void main(String[] args) {
Scanner inr = new Scanner(System.in);
int n = inr.nextInt();
int k = 0, sum = 0;
for (int i = 1; i <= n; ++i, k = 0) {
for (int space = 1; space <= n - i; ++space) {
System.out.print(" ");
}
while (k != 2 * i - 1) {
System.out.print("* ");
sum += 1;
++k;
}
System.out.println();
}
System.out.println(sum);
}
}Explanation: This program generates a pyramid of ’’ characters with a height of ‘n’ and calculates the total number of ’’ characters in the pyramid. It uses nested loops to print the pyramid and increments the ‘sum’ variable for each ’*’ character printed.
Java Week 8: Q2 - Pascal Pyramid of Stars
Question 2: Write a program that prints a Pascal pyramid of ’*’ with a height ‘l’.
import java.util.*;
public class Pattern2 {
public static void main(String[] args) {
Scanner inr = new Scanner(System.in);
int l = inr.nextInt();
int i, j;
int space = l - 1;
for (i = 0; i < l; i++) {
for (j = 0; j < space; j++) {
System.out.print(" ");
}
for (j = 0; j <= i; j++) {
System.out.print("* ");
}
System.out.print("\n");
space--;
}
}
}Explanation: This program prints a Pascal pyramid of ’’ characters with a height of ‘l’. It uses nested loops to control the number of ’’ characters and spaces printed on each line.
Java Week 8: Q3 - Pyramid of Numbers and Sum
Question 3: Write a program that prints a pyramid of numbers with a height ‘n’ and also prints the sum of all the numbers in the pyramid.
import java.util.*;
public class Pattern3 {
public static void main(String[] args) {
Scanner inr = new Scanner(System.in);
int n = inr.nextInt();
int k = 1, sum = 0;
for (int i = 1; i <= n; ++i, k = 1) {
for (int space = 1; space <= n - i; ++space) {
System.out.print(" ");
}
while (k <= 2 * i - 1) {
System.out.print(k + " ");
sum += k;
++k;
}
System.out.println();
}
System.out.println(sum);
}
}Explanation: This program generates a pyramid of numbers with a height of ‘n’ and calculates the sum of all the numbers in the pyramid. It uses nested loops to print the pyramid and adds each number to the ‘sum’ variable.
Java Week 8: Q4 - Symmetric Pascal’s Triangle
Question 4: Write a program to print a symmetric Pascal’s triangle of ’*’ characters with a height ‘l’ of odd length. If ‘l’ is even, the program should print “Invalid line number.”
import java.util.*;
public class Pattern4 {
public static void main(String[] args) {
Scanner inr = new Scanner(System.in);
int l = inr.nextInt();
int ul = 0; // Upper Line
int ll = 0; // Lower Line
if (l % 2 != 0) {
ul = (l / 2) + 1;
ll = l - ul;
// Code for upper half
for (int i = 1; i <= ul; i++) {
for (int s = 1; s <= (ul - i); s++) {
System.out.print(" ");
}
for (int j = 1; j <= i; j++) {
System.out.print("* ");
}
System.out.println();
}
// Code for lower half
int llc = ll;
for (int i = 1; i <= ll; i++) {
for (int s = llc; s < ll; s++) {
System.out.print(" ");
}
for (int j = 1; j <= (ll - i + 1); j++) {
System.out.print(" *");
}
llc--;
System.out.println();
}
} else {
System.out.print("Invalid line number");
}
}
}Explanation: This program prints a symmetric Pascal’s triangle of ’*’ characters with a height of ‘l’ if ‘l’ is odd. If ‘l’ is even, it prints “Invalid line number.” It uses conditional statements and loops to create the pattern.
Java Week 8: Q5 - 7 Segment Display for Digits
Question 5: Write a program to display any digit ‘n’ from 0-9 using a “7 segment display.”
import java.util.*;
public class Pattern5 {
private static final Map<Integer, Integer> encodings = new HashMap<Integer, Integer>();
static {
encodings.put(0, 0x7E);
encodings.put(1, 0x30);
encodings.put(2, 0x6D);
encodings.put(3, 0x79);
encodings.put(4, 0x33);
encodings.put(5, 0x5B);
encodings.put(6, 0x5F);
encodings.put(7, 0x70);
encodings.put(8, 0x7F);
encodings.put(9, 0x7B);
}
public static void printDigit(int digit) {
int code = encode(digit);
char[] bits =
String.format("%7s", Integer.toBinaryString(code))
.replace(' ', '0').toCharArray();
lightSegment(bits[0] == '1', " _ \n", " \n");
lightSegment(bits[5] == '1', "|", " ");
lightSegment(bits[6] == '1', "_", " ");
lightSegment(bits[1] == '1', "|\n", " \n");
lightSegment(bits[4] == '1', "|", " ");
lightSegment(bits[3] == '1', "_", " ");
lightSegment(bits[2] == '1', "|\n", "\n");
}
private static void lightSegment(boolean on, String onValue, String offValue) {
System.out.print(on ? onValue : offValue);
try {
Thread.sleep(0);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
private static int encode(int digit) {
return encodings.containsKey(digit) ? encodings.get(digit) : 0x00;
}
public static void main(String[] args) {
Scanner inr = new Scanner(System.in);
int n = inr.nextInt();
printDigit(n);
}
}Explanation: This program displays a digit (0-9) using a “7 segment display” pattern. It uses a predefined encoding map to determine which segments should be lit to represent the digit. The printDigit function handles the display, and encode maps digits to their corresponding binary patterns. The program then prints the segments accordingly.
These solutions cover a variety of advanced patterns and techniques, enhancing your Java programming skills. Continue practicing and exploring new challenges to become a proficient Java programmer. Stay tuned for more Java NPTEL solutions in the upcoming weeks!