Create Next Greater Element.java

Author: py3-coder

Stack_Interview Problem/Next Greater Element.java

@@ -0,0 +1,33 @@
+//Problem  Statement : https://practice.geeksforgeeks.org/problems/next-larger-element-1587115620/1?utm_source=gfg&utm_medium=article&utm_campaign=bottom_sticky_on_article
+
+class Solution
+{
+    //Function to find the next greater element for each element of the array.
+    public static long[] nextLargerElement(long[] arr, int n)
+    { 
+        // Your code here
+        //Lets play with Stack::
+        //Brute Force :::
+        long[] res = new long[n];
+        int k=n-1;
+        Stack<Long> st = new Stack();
+        for(int i=n-1;i>=0;i--){
+            if(st.isEmpty()){
+                res[i] =-1;
+            }else if(st.peek()>arr[i]){
+                res[i] =st.peek();
+            }else{
+                while(!st.isEmpty() && st.peek()<=arr[i]){
+                    st.pop();
+                }
+                if(st.isEmpty()){
+                    res[i] =-1;
+                }else{
+                    res[i] =st.peek();
+                }
+            }
+            st.push(arr[i]);
+        }
+        return res;
+    } 
+}