CODEWITHSUNDEEP
javabinary-search
rockz3r
rockz3r

Reputation: 61

Iterative binary search does not complete

I have written binary search using a while loop. It searches for the matching name and prints their aim which is in a parallel array b[]

import java.util.*;

class binarysearch {
    public static void calc() {
        Scanner sc = new Scanner(System.in);
        int l = 0, mid = 0, u = 4, i, f = 0;
        String ns;
        String a[] = { "Amar", "Camelia", "Debopriya", "Gargi", "Harmeet" };
        String b[] = { "Astronaut", "Artist", "Dancer", "Singer", "Engineer" };
        System.out.println("Enter name to be Searched");
        ns = sc.next();
        while (l <= u) {
            mid = (int) ((l + u) / 2);
            if (ns.compareTo(a[mid]) > 0) {
                l = mid + 1;
            } else if (ns.compareTo(a[mid]) < 0) {
                u = mid - 1;
            } else if (ns.compareTo(a[mid]) == 0) {
                f = 1;
            }
        }

        if (f == 1) {
            System.out.println("Name is " + a[mid] + " aim is " + b[mid]);
        } else {
            System.out.println("Name Not Found");
        }
    }
}

The problem is that there is no output in terminal window. I can see the message of Enter name to be Searched as well as when I'm typing a string and pressing enter. However nothing else is happening. Does anyone know what is wrong?

Upvotes: 1

Views: 72

Answers (1)

James Wierzba
James Wierzba

Reputation: 17538

When a match is found, you are not exiting the loop. It is an infinite loop. Try this:

...
        while(l<=u)
        {
            mid=(int) ((l+u)/2);
            if(ns.compareTo(a[mid]) > 0)
            {
                l=mid+1;
            }
            else if(ns.compareTo(a[mid])<0)
            {
                u=mid-1;
            }
            else if(ns.compareTo(a[mid])==0)
            {
                f=1;
                break; //<- add this statement
            }
        }
...

With this change, I get this output:

Enter name to be Searched

Gargi

Name is Gargi aim is Singer

Upvotes: 3

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