GFG mathematics 03-2

 package com.company;

import java.util.Scanner;

public class CWR_Mathematics_Gfg03 {
//    sieve 3 --> most efficient
public static void stieve3(int n){
    boolean [] isPrime = new boolean[n+1];
    for(int i=0;i<n+1;i++){
        isPrime[i] = true;
    }
    for(int j=2 ; j<=n ;j++) {
        if(isPrime[j]) {
            System.out.println(j);
            for(int i=j*j;i<=n;i=j+i){
                isPrime[i] = false;
            }
        }
        }
    }


//    Sieve 2
public static void stieve2(int n){
    boolean [] isPrime = new boolean[n+1];
    for(int i=0;i<n+1;i++){
        isPrime[i] = true;
    }

    for(int j=2 ; j*j<=n ;j++) {
        if(isPrime[j]) {
            for( int a= j*j;a<=n ;a=a+j){
                isPrime[a]=false;
            }
        }
    }
    for(int i=2;i<=n;i++){
        if(isPrime[i]){
            System.out.println(i);
        }
    }
}
//    Sieve
    public static void stieve(int n){
      boolean [] isPrime = new boolean[n+1];
        for(int i=0;i<n+1;i++){
            isPrime[i] = true;
        }

        for(int j=2 ; j*j<=n ;j++) {
            if(isPrime[j]) {
                for( int a= 2*j;a<=n ;a=a+j){
                    isPrime[a]=false;
                }
            }
        }
        for(int i=2;i<=n;i++){
            if(isPrime[i]){
                System.out.println(i);
            }
        }
    }
//    computing power
    public static int printPower(int x,int n){
        if(n==0){
            return 1;
        }
        int temp = x;
        for(int i=1;i<n;i++){
            temp = temp*x;
        }
        return temp;
    }
//    sieve of eratosthenes
    public static void printPrime(int n){
        int j = 1;
        for(int i=2;i<=n;i++){
            if (isPrime(i)) {
                System.out.println(j + "." +i);
                j++;
            }
        }
    }
//    All divisor of a number
//    3
    public static void print(int n){
        int i;
        for(i=1; i*i<n ;i++){
            if(n%i==0){
                System.out.println(i);
            }
        }
        for(;i>=1;i--){
            if (n % i == 0) {
                System.out.println(n/i);
            }
        }
    }
//    1
    public static void printingDivisor(int n){
        for(int i= 1; i*i<=n;i++){
            if(n%i==0){
                System.out.println(i);
                if(i!=n/i){
                    System.out.println(n/i);
                }
            }
        }
    }
//    2
    public static void printAllDivisor(int n){
        for(int i=1;i<=n;i++){
            if(n%i==0){
                System.out.println(i);
            }
        }
    }
    public static void printPrimeNumbers(int n){
        if(n<=1){
            return;
        }
      while(n%2==0){
            System.out.println(2);
            n = n/2;
        }
        while (n%3==0){
            System.out.println(3);
            n = n/3;
        }
        for(int i = 5; i*i<=n ;i=i+5){
            while(n%i==0){
                System.out.println(i);
                n = n/i;
            }
            while(n%(i+2)==0){
                System.out.println(i+2);
                n = n/(i+2);
            }
        }
        if(n>3){
            System.out.println(n);
        }
    }
    public static void primeFactors(int n){
        for(int i=0;i<=n;i++){
            if(isPrime(i)){
                int x = i;
                while(n%x==0){
                    System.out.println(i);
                    x = x*i;
                }
            }
        }
    }
    public static boolean isPrime(int n){

            if(n==2 || n==3){
            return true;
        }
       else if(n==1 || n%2 == 0 ||n%3 ==0 ){
            return false;
        }
        for(int i = 5; i*i<=n ; i=i+6){

            if(n%i==0 || n%(i+2)==0){
                return false;
            }
        }
        return true;
    }
    public static int gcd(int a,int b){
        if( b== 0){
            return a;
        }
        return gcd(b,a%b);
    }
    public static int lcm1(int a, int b){
        return a*b/gcd(a,b);
    }
    public static int lcm(int a,int b) {
        int n = Math.max(a,b);

        while(true){
            if(n%a == 0 && n%b == 0){
                return n;
            }
            n++;
        }
    }
    public static void main(String[] args) {
        System.out.println("Enter the number");
        Scanner sc = new Scanner(System.in);
//        System.out.println(printPower(sc.nextInt(),sc.nextInt()));
//        printPrime(sc.nextInt());
//        System.out.println(-2%2);
        stieve3(20);
    }
}