Java algoritmlari

Oldingi boblarda ma’lumotlar tuzilmalari (ArrayList, HashMap va boshqalar) ma’lumotlarni saqlash va tartibga solish uchun qanday ishlatilishini o‘rgandingiz.

Algoritmlar ma’lumotlar tuzilmalarini saralash, ulardan qidirish va ularni qayta ishlash orqali masalalarni yechish uchun ishlatiladi.

Java tilida ko‘plab foydali algoritmlar Collections sinfiga (java.util paketida joylashgan) allaqachon o‘rnatilgan, shuning uchun ularni noldan yozishingiz shart emas.

Qidirish

Ro‘yxatdan elementlarni topish uchun Java yordamchi metodlarni taqdim etadi. Eng ko‘p ishlatiladigani Collections.binarySearch() bo‘lib, u saralangan ro‘yxatda qidiradi:

Misol

Saralangan ArrayList ichidan elementni qidirish:

import java.util.*;

public class Main {
  public static void main(String[] args) {
    ArrayList<String> names = new ArrayList<>();
    names.add("Liam");
    names.add("Jenny");
    names.add("Kasper");
    names.add("Angie");

    Collections.sort(names); // must be sorted first
    int index = Collections.binarySearch(names, "Angie");
    System.out.println("Angie is at index: " + index);
  }
}

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Saralash

Saralash eng keng tarqalgan algoritmlardan biridir. ArrayList bilan ishlaganda elementlarni saralash uchun Collections.sort() metodidan foydalanishingiz mumkin:

Misol

Sonlar ro‘yxatini saralash:

import java.util.*;

public class Main {
  public static void main(String[] args) {
    ArrayList<Integer> numbers = new ArrayList<>();
    numbers.add(5);
    numbers.add(1);
    numbers.add(7);
    numbers.add(3);
    numbers.add(9);

    Collections.sort(numbers);
    System.out.println(numbers); // [1, 3, 5, 7, 9]
  }
}

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Collections.sort(list, Collections.reverseOrder()) yordamida teskari tartibda ham saralashingiz mumkin:

Misol

ArrayList elementlarini kamayish tartibida saralash:

import java.util.*;

public class Main {
  public static void main(String[] args) {
    ArrayList<Integer> numbers = new ArrayList<>();
    numbers.add(5);
    numbers.add(1);
    numbers.add(7);
    numbers.add(3);
    numbers.add(9);

    Collections.sort(numbers, Collections.reverseOrder());
    System.out.println(numbers); // [9, 7, 5, 3, 1]
  }
}

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Aylanib chiqish

Elementlarni aylanib chiqish (sikl) ham keng tarqalgan algoritmlardan biri. Buning uchun for-each siklidan yoki Iterator interfeysidan foydalanishingiz mumkin:

Misol

ArrayList bo‘ylab for-each yordamida aylanib chiqish:

import java.util.*;

public class Main {
  public static void main(String[] args) {
    ArrayList<String> colors = new ArrayList<>();
    colors.add("Red");
    colors.add("Green");
    colors.add("Blue");

    for (String c : colors) {
      System.out.println(c);
    }
  }
}

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Misol

ArrayList bo‘ylab Iterator yordamida aylanib chiqish:

import java.util.*;

public class Main {
  public static void main(String[] args) {
    ArrayList<String> colors = new ArrayList<>();
    colors.add("Red");
    colors.add("Green");
    colors.add("Blue");

    Iterator<String> it = colors.iterator();
    while (it.hasNext()) {
      System.out.println(it.next());
    }
  }
}

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Boshqa foydali algoritmlar

Collections sinfida yana ko‘plab algoritmlar mavjud, masalan:

Collections.max() - eng katta elementni topish
Collections.min() - eng kichik elementni topish
Collections.shuffle() - elementlarni tasodifiy aralashtirish
Collections.frequency() - element necha marta uchrashini sanash
Collections.swap() - ro‘yxatdagi ikki elementning o‘rnini almashtirish

Ushbu misolda ArrayList ichidagi eng katta va eng kichik elementni topish uchun Collections.max() va Collections.min() metodlaridan foydalanamiz:

Misol

import java.util.*;

public class Main {
  public static void main(String[] args) {
    ArrayList<Integer> numbers = new ArrayList<>();
    numbers.add(5);
    numbers.add(1);
    numbers.add(7);
    numbers.add(3);
    numbers.add(9);

    System.out.println("Max: " + Collections.max(numbers));
    System.out.println("Min: " + Collections.min(numbers));
  }
}

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ArrayList elementlarini tasodifiy aralashtirish:

Misol

import java.util.*;

public class Main {
  public static void main(String[] args) {
    ArrayList<String> cards = new ArrayList<>();
    cards.add("Ace");
    cards.add("King");
    cards.add("Queen");
    cards.add("Jack");

    Collections.shuffle(cards);
    System.out.println(cards);
  }
}

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Collections.frequency() element ro‘yxatda necha marta uchrashini sanaydi:

Misol

import java.util.*;

public class Main {
  public static void main(String[] args) {
    ArrayList<String> fruits = new ArrayList<>();
    fruits.add("Apple");
    fruits.add("Banana");
    fruits.add("Orange");
    fruits.add("Banana");
    fruits.add("Mango");

    int count = Collections.frequency(fruits, "Banana");
    System.out.println("Banana appears: " + count + " times");
  }
}

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Collections.swap() ro‘yxatdagi ikki elementning o‘rnini almashtiradi:

Misol

import java.util.*;

public class Main {
  public static void main(String[] args) {
    ArrayList<String> fruits = new ArrayList<>();
    fruits.add("Apple");
    fruits.add("Banana");
    fruits.add("Orange");
    fruits.add("Mango");

    Collections.swap(fruits, 0, 2); // Swap first and third element
    System.out.println(fruits);
  }
}

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Xulosa

Algoritm — masalani yechish uchun bajariladigan amallar tartibi.
Java Collections sinfida o‘rnatilgan algoritmlarni taqdim etadi.
Keng tarqalgan algoritmlarga qidirish, saralash, aylanib chiqish va min/max qiymatlarni topish kiradi.
Algoritmlar dasturlaringizni yanada kuchli va samarali qilish uchun ma’lumotlar tuzilmalari (ArrayList, HashSet va boshqalar) bilan birgalikda ishlaydi.

Collections bo‘yicha to‘liq ma’lumotnoma

Barcha Collections metodlarining to‘liq ro‘yxati uchun Java Collections ma’lumotnomasi sahifasiga o‘ting.

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