Please Solve for (b + c) Q) Answer the questions regarding the following program

Question

Please Solve for (b + c)

Q) Answer the questions regarding the following program

import java.util.ArrayList;
public class Eratosthenes {
public static void main(String []args) {
ArrayList<Integer> al = new ArrayList<>();
int n = 120;
for(int i = 0; i < n; i++) {
al.add(1);
}
al.set(0,0);
al.set(1,0);
for(int i = 2; i < n; i++) {
for(int j = 2; i*j < n; j++) {
al.set(i*j,0);
}
}
for(int i = 0; i < n; i++) {
if (al.get(i) > 0) {
System.out.println(i);
}
}
}
}

(a) Execute this program and submit the result
Answer:
2
3
5
7
11
13
17
19
23
29
31
37
41
43
47
53
59
61
67
71
73
79
83
89
97
101
103
107
109
113

(b) What are the common characteristics of the printed numbers. Explain briefly.
Answer: ???

(c) The following program execute the same algorithm as the above. Complete the following program.

import java.util.ArrayList;
public class Prime {
public static void main(String []args) {
ArrayList<Object> al = new ArrayList<>();
int n = 120;
for(int i = 0; i < n; i++) {
_________;
}
___________;
___________;
for(int i = 2; i < n; i++) {
for(int j = 2; i*j < n; j++) {
_____________;
}
}
for(int i = 0; i < n; i++) {
if (______________________) {
System.out.println(i);
}
}
}
}

Explanation / Answer

b) The output is a list of prime numbers between 0 to 120

c) Inorder to convert an object to int(Typecasting) you need to use (int) object .

import java.util.ArrayList;

public class Prime {
public static void main(String []args) {
ArrayList<Object> al = new ArrayList<>();
int n = 120;
for(int i = 0; i < n; i++) {
al.add(1);
}

al.set(0,0);
al.set(1,0);
for(int i = 2; i < n; i++) {
for(int j = 2; i*j < n; j++) {
al.set(i*j,0);
}
}
for(int i = 0; i < n; i++) {
if ((int) al.get(i) > 0) {
System.out.println(i);
}

}
}
}

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