'전체 글'에 해당되는 글 88건

prime   = 소수 (1과 자기자신과 나누어 지는수)

semiprime =반소수 (자기자신및 다른 소수와 곱한값)

P  와 Q 사이에 반소수의 개수를 구하면 되는거다.

아래는 나의 솔루선

너무 어렵고 힘든 문제다 아래소스는 답만 나오는데 중점을 두었지 전혀 만족스러운 코드가 아니다.

담에 다시 도전하겠다.

// you can also use imports, for example:

import java.util.*;

// you can write to stdout for debugging purposes, e.g.

// System.out.println("this is a debug message");

class Solution {

    public int[] solution(int N, int[] P, int[] Q) {

        //first, get  primes and then get semiprimes.

        Set<Integer> prime = new LinkedHashSet<Integer>();

        for(int i=2; i< N; i++){

            prime.add(i);

            for(int j =1; j<i; j++){

                if( i%j == 0 && j !=1 && j !=i){

                    prime.remove(i);

                }

            }

        }

       // System.out.println("prime = " + prime);

        Set<Integer> semiPrime = new LinkedHashSet<Integer>();

        for(int i=0; i< prime.size(); i++){

            int getPrime = prime.stream().skip(prime.size()-(i+1)).findFirst().get();

             semiPrime.add(getPrime * getPrime);

             for(int j =1; j< prime.size(); j++){

                 int getPrime1 = prime.stream().skip(prime.size()-(i+1)).findFirst().get();

                 int getPrime2 = prime.stream().skip(prime.size()-(j+1)).findFirst().get();

               semiPrime.add(getPrime1 * getPrime2);

            }

        }

        //System.out.println("semiPrime = " + semiPrime);

        List<Integer> list = new ArrayList<Integer>(semiPrime);

        int[] ret = new int[3];

        int cnt = 0;

        for(int i=0 ;i < P.length; i++){

               for(int j =0; j< list.size() ; j++){

                       if(list.get(j) >= P[i] && list.get(j)  <= Q[i] ){

                           cnt++;

                     }

               }

               ret[i] = cnt;

               cnt = 0;

        }

        // System.out.println("ret = " + ret);

        return ret;

    }

}

Process:

• An executing instance of a program is called a process.
• Some operating systems use the term ‘task‘ to refer to a program that is being executed.
• A process is always stored in the main memory also termed as the primary memory or random access memory.
• Therefore, a process is termed as an active entity. It disappears if the machine is rebooted.
• Several process may be associated with a same program.
• On a multiprocessor system, multiple processes can be executed in parallel.
• On a uni-processor system, though true parallelism is not achieved, a process scheduling algorithm is applied and the processor is scheduled to execute each process one at a time yielding an illusion of concurrency.
• Example: Executing multiple instances of the ‘Calculator’ program. Each of the instances are termed as a process.

Thread:

• A thread is a subset of the process.
• It is termed as a ‘lightweight process’, since it is similar to a real process but executes within the context of a process and shares the same resources allotted to the process by the kernel.
• Usually, a process has only one thread of control – one set of machine instructions executing at a time.
• A process may also be made up of multiple threads of execution that execute instructions concurrently.
• Multiple threads of control can exploit the true parallelism possible on multiprocessor systems.
• On a uni-processor system, a thread scheduling algorithm is applied and the processor is scheduled to run each thread one at a time.
• All the threads running within a process share the same address space, file descriptors, stack and other process related attributes.
• Since the threads of a process share the same memory, synchronizing the access to the shared data withing the process gains unprecedented importance.