A bináris keresés egy kulcselem több elem közül való keresésére szolgál. A bináris keresés gyorsabb, mint a lineáris keresés.
len of string java
Bináris keresés esetén a tömbelemeknek növekvő sorrendben kell lenniük. Ha rendezetlen tömbje van, a tömböt a segítségével rendezheti Arrays.sort(arr) módszer.
Bináris keresési példa Java nyelven
Lássunk egy példát a java bináris keresésére.
class BinarySearchExample{ public static void binarySearch(int arr[], int first, int last, int key){ int mid = (first + last)/2; while( first <= last ){ if ( arr[mid] system.out.println('element is not found!'); } public static void main(string args[]){ int arr[]="{10,20,30,40,50};" key="30;" binarysearch(arr,0,last,key); < pre> <span> Test it Now </span> <p>Output:</p> <pre> Element is found at index: 2 </pre> <h2>Binary Search Example in Java using Recursion</h2> <p>Let's see an example of binary search in java where we are going to search an element from an array using recursion.</p> <pre> class BinarySearchExample1{ public static int binarySearch(int arr[], int first, int last, int key){ if (last>=first){ int mid = first + (last - first)/2; if (arr[mid] == key){ return mid; } if (arr[mid] > key){ return binarySearch(arr, first, mid-1, key);//search in left subarray }else{ return binarySearch(arr, mid+1, last, key);//search in right subarray } } return -1; } public static void main(String args[]){ int arr[] = {10,20,30,40,50}; int key = 30; int last=arr.length-1; int result = binarySearch(arr,0,last,key); if (result == -1) System.out.println('Element is not found!'); else System.out.println('Element is found at index: '+result); } } </pre> <span> Test it Now </span> <p>Output:</p> <pre> Element is found at index: 2 </pre> <h2>Binary Search Example in Java using Arrays.binarySearch()</h2> <pre> import java.util.Arrays; class BinarySearchExample2{ public static void main(String args[]){ int arr[] = {10,20,30,40,50}; int key = 30; int result = Arrays.binarySearch(arr,key); if (result <0) system.out.println('element is not found!'); else found at index: '+result); } < pre> <span> Test it Now </span> <p>Output:</p> <pre> Element is found at index: 2 </pre></0)></pre></=> Példa bináris keresésre a Java nyelven a Recursion használatával
Lássunk egy példát a java bináris keresésére, ahol rekurzió segítségével fogunk keresni egy elemet egy tömbből.
class BinarySearchExample1{ public static int binarySearch(int arr[], int first, int last, int key){ if (last>=first){ int mid = first + (last - first)/2; if (arr[mid] == key){ return mid; } if (arr[mid] > key){ return binarySearch(arr, first, mid-1, key);//search in left subarray }else{ return binarySearch(arr, mid+1, last, key);//search in right subarray } } return -1; } public static void main(String args[]){ int arr[] = {10,20,30,40,50}; int key = 30; int last=arr.length-1; int result = binarySearch(arr,0,last,key); if (result == -1) System.out.println('Element is not found!'); else System.out.println('Element is found at index: '+result); } } Tesztelje most Kimenet:
Element is found at index: 2
Példa bináris keresésre Java nyelven az Arrays.binarySearch() használatával
import java.util.Arrays; class BinarySearchExample2{ public static void main(String args[]){ int arr[] = {10,20,30,40,50}; int key = 30; int result = Arrays.binarySearch(arr,key); if (result <0) system.out.println(\'element is not found!\'); else found at index: \'+result); } < pre> <span> Test it Now </span> <p>Output:</p> <pre> Element is found at index: 2 </pre></0)>