V tem primeru se bomo naučili izvajati binarni algoritem iskanja v Javi.
Če želite razumeti ta primer, morate poznati naslednje programske teme Java:
- Java while in do … while Loop
- Izjava Java, če … drugače
- Java nizi
Primer: Java program za izvajanje algoritma binarnega iskanja
import java.util.Scanner; // Binary Search in Java class Main ( int binarySearch(int array(), int element, int low, int high) ( // Repeat until the pointers low and high meet each other while (low <= high) ( // get index of mid element int mid = low + (high - low) / 2; // if element to be searched is the mid element if (array(mid) == element) return mid; // if element is less than mid element // search only the left side of mid if (array(mid) < element) low = mid + 1; // if element is greater than mid element // search only the right side of mid else high = mid - 1; ) return -1; ) public static void main(String args()) ( // create an object of Main class Main obj = new Main(); // create a sorted array int() array = ( 3, 4, 5, 6, 7, 8, 9 ); int n = array.length; // get input from user for element to be searched Scanner input = new Scanner(System.in); System.out.println("Enter element to be searched:"); // element to be searched int element = input.nextInt(); input.close(); // call the binary search method // pass arguments: array, element, index of first and last element int result = obj.binarySearch(array, element, 0, n - 1); if (result == -1) System.out.println("Not found"); else System.out.println("Element found at index " + result); ) )
Izhod 1
Vnesite element, ki ga želite iskati: 6 Element najdemo v indeksu 3
Tu smo uporabili razred Java Scanner Class, da uporabnik vnese podatke. Na podlagi vnosa uporabnika smo z binarnim iskanjem preverili, ali je element prisoten v matriki.
Za isto nalogo lahko uporabimo tudi rekurzivni klic.
int binarySearch(int array(), int element, int low, int high) ( if (high>= low) ( int mid = low + (high - low) / 2; // check if mid element is searched element if (array(mid) == element) return mid; // Search the left half of mid if (array(mid)> element) return binarySearch(array, element, low, mid - 1); // Search the right half of mid return binarySearch(array, element, mid + 1, high); ) return -1; )
Tu se metoda binarySearch()sama pokliče, dokler elementa ne najde ali ifstanje ne uspe.
Če želite izvedeti več o binarnem algoritmu iskanja, obiščite Binarni algoritem iskanja.
