DEV Community

loading...
Cover image for Day 26: Merge Sort

Day 26: Merge Sort

mattryanmtl profile image Matt Ryan ・1 min read

Alt Text

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.Arrays;

public class MergeSort {

    // Function to merge the two sorted arrays
    static void merge(int[] array,int low,int mid,int high){

        int i,j,k;
        int[] c= new int[high-low+1];
        k = 0;
        i=low;
        j=mid+1;

        while(i<=mid && j<=high){

            if(array[i]<=array[j]){

                c[k++] = array[i++];

            }

            else{

                c[k++] = array[j++];

            }
        }

        while(i<=mid){

            c[k++] = array[i++];

        }

        while(j<=high){

            c[k++] = array[j++];

        }

        k=0;

        for(i = low; i<=high; i++){

            array[i] = c[k++];

        }
    }

    // Function implementing the merge sort
    static void mergeSort(int[] array,int low, int high){

        if(high-low+1>1){

            int mid = (low+high)/2;
            mergeSort(array,low,mid);
            mergeSort(array,mid+1,high);
            merge(array,low,mid,high);
        }
    }

    // Function to read the input and display the output
    public static void main(String[] args) {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        int size;

        System.out.println("Enter the size of the array");
        try {
            size = Integer.parseInt(br.readLine());
        } catch (Exception e) {
            System.out.println("Invalid Input");
            return;
        }

        int[] array = new int[size];

        System.out.println("Enter array elements");

        int i;
        for (i = 0; i < array.length; i++) {
            try {
                array[i] = Integer.parseInt(br.readLine());
            } catch (Exception e) {
                System.out.println("An error Occurred");
            }
        }

        System.out.println("The initial array is");
        System.out.println(Arrays.toString(array));
        mergeSort(array,0,array.length-1);
        System.out.println("The sorted array is");
        System.out.println(Arrays.toString(array));
    }
}
Enter fullscreen mode Exit fullscreen mode

Discussion (0)

Forem Open with the Forem app