Next Greater Element

Given an array, print the Next Greater Element (NGE) for every element. The Next greater Element for an element x is the first greater element on the right side of x in array. Elements for which no greater element exist, consider next greater element as -1.

Input : {0,1,2,6,8,87,12,43,23,54,66}

0 --> 87

1 --> 87

2 --> 87

6 --> 87

8 --> 87

87 --> -1

12 --> 66

43 --> 66

23 --> 66

54 --> 66

66 --> -1

package core.geeks;

import java.io.IOException;

public class NextGreatestElementUnsortedArr {

       public static void main(String[] args) throws IOException {

             

              int[] arr = new int[]{0,1,2,6,8,87,12,43,23,54,66};

             

              int[] maxDynaArr = new int[arr.length];

             

              maxDynaArr[arr.length-1] = -1;

             

              if(arr[arr.length-1]>arr[arr.length-2]) {

                     maxDynaArr[arr.length-2] = arr[arr.length-1];

              } else {

                     maxDynaArr[arr.length-2] = -1;

              }

             

              int preTemp = Math.max(Integer.MIN_VALUE, maxDynaArr[arr.length-2]);

             

              for(int i=arr.length-3;i>=0;i--) {

                    

                     int temp = Math.max(arr[i+1],maxDynaArr[i+2]);

                    

                     preTemp = Math.max(preTemp,temp);

                     if(preTemp>arr[i]) {

                           maxDynaArr[i] = preTemp;

                     } else {

                           maxDynaArr[i] = -1;

                     }

                    

              }

             

              for (int i = 0; i < maxDynaArr.length; i++) {

                     System.out.println(arr[i] + " --> "+maxDynaArr[i]);

              }

       }

}