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Next Larger element in n-ary tree
• Difficulty Level : Medium
• Last Updated : 02 Jan, 2020

Given a generic tree and a integer x. Find and return the node with next larger element in the tree i.e. find a node just greater than x. Return NULL if no node is present with value greater than x.

For example, in the given tree

x = 10, just greater node value is 12

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

The idea is maintain a node pointer res, which will contain the final resultant node.
Traverse the tree and check if root data is greater than x. If so, then compare the root data with res data.
If root data is greater than n and less than res data update res.

## C++

 `// CPP program to find next larger element ` `// in an n-ary tree. ` `#include ` `using` `namespace` `std; ` ` `  `// Structure of a node of an n-ary tree ` `struct` `Node { ` `    ``int` `key; ` `    ``vector child; ` `}; ` ` `  `// Utility function to create a new tree node ` `Node* newNode(``int` `key) ` `{ ` `    ``Node* temp = ``new` `Node; ` `    ``temp->key = key; ` `    ``return` `temp; ` `} ` ` `  `void` `nextLargerElementUtil(Node* root, ``int` `x, Node** res) ` `{ ` `    ``if` `(root == NULL) ` `        ``return``; ` ` `  `    ``// if root is less than res but greater than  ` `    ``// x update res ` `    ``if` `(root->key > x)  ` `        ``if` `(!(*res) || (*res)->key > root->key) ` `            ``*res = root;     ` ` `  `    ``// Number of children of root ` `    ``int` `numChildren = root->child.size(); ` ` `  `    ``// Recur calling for every child ` `    ``for` `(``int` `i = 0; i < numChildren; i++) ` `        ``nextLargerElementUtil(root->child[i], x, res); ` ` `  `    ``return``; ` `} ` ` `  `// Function to find next Greater element of x in tree ` `Node* nextLargerElement(Node* root, ``int` `x) ` `{ ` `    ``// resultant node ` `    ``Node* res = NULL; ` ` `  `    ``// calling helper function ` `    ``nextLargerElementUtil(root, x, &res); ` ` `  `    ``return` `res; ` `} ` ` `  `// Driver program ` `int` `main() ` `{ ` `    ``/*   Let us create below tree ` `   ``*             5 ` `   ``*         /   |  \ ` `   ``*         1   2   3 ` `   ``*        /   / \   \ ` `   ``*       15  4   5   6 ` `   ``*/` ` `  `    ``Node* root = newNode(5); ` `    ``(root->child).push_back(newNode(1)); ` `    ``(root->child).push_back(newNode(2)); ` `    ``(root->child).push_back(newNode(3)); ` `    ``(root->child[0]->child).push_back(newNode(15)); ` `    ``(root->child[1]->child).push_back(newNode(4)); ` `    ``(root->child[1]->child).push_back(newNode(5)); ` `    ``(root->child[2]->child).push_back(newNode(6)); ` ` `  `    ``int` `x = 5; ` ` `  `    ``cout << ``"Next larger element of "` `<< x << ``" is "``; ` `    ``cout << nextLargerElement(root, x)->key << endl; ` ` `  `    ``return` `0; ` `} `

## Java

 `// Java program to find next larger element ` `// in an n-ary tree. ` `import` `java.util.*; ` ` `  `class` `GFG ` `{ ` ` `  `// Structure of a node of an n-ary tree ` `static` `class` `Node ` `{ ` `    ``int` `key; ` `    ``Vector child; ` `}; ` `static` `Node res; ` ` `  `// Utility function to create a new tree node ` `static` `Node newNode(``int` `key) ` `{ ` `    ``Node temp = ``new` `Node(); ` `    ``temp.key = key; ` `    ``temp.child = ``new` `Vector<>(); ` `    ``return` `temp; ` `} ` ` `  `static` `void` `nextLargerElementUtil(Node root, ``int` `x) ` `{ ` `    ``if` `(root == ``null``) ` `        ``return``; ` ` `  `    ``// if root is less than res but  ` `    ``// greater than x, update res ` `    ``if` `(root.key > x)  ` `        ``if` `((res == ``null` `|| (res).key > root.key)) ` `            ``res = root;  ` ` `  `    ``// Number of children of root ` `    ``int` `numChildren = root.child.size(); ` ` `  `    ``// Recur calling for every child ` `    ``for` `(``int` `i = ``0``; i < numChildren; i++) ` `        ``nextLargerElementUtil(root.child.get(i), x); ` ` `  `    ``return``; ` `} ` ` `  `// Function to find next Greater element  ` `// of x in tree ` `static` `Node nextLargerElement(Node root, ``int` `x) ` `{ ` `    ``// resultant node ` `    ``res = ``null``; ` ` `  `    ``// calling helper function ` `    ``nextLargerElementUtil(root, x); ` ` `  `    ``return` `res; ` `} ` ` `  `// Driver Code ` `public` `static` `void` `main(String[] args) ` `{ ` `    ``/* Let us create below tree ` `    ``*             5 ` `    ``*         / | \ ` `    ``*         1 2 3 ` `    ``*     / / \ \ ` `    ``*     15 4 5 6 ` `    ``*/` `    ``Node root = newNode(``5``); ` `    ``(root.child).add(newNode(``1``)); ` `    ``(root.child).add(newNode(``2``)); ` `    ``(root.child).add(newNode(``3``)); ` `    ``(root.child.get(``0``).child).add(newNode(``15``)); ` `    ``(root.child.get(``1``).child).add(newNode(``4``)); ` `    ``(root.child.get(``1``).child).add(newNode(``5``)); ` `    ``(root.child.get(``2``).child).add(newNode(``6``)); ` ` `  `    ``int` `x = ``5``; ` ` `  `    ``System.out.print(``"Next larger element of "` `+ ` `                                    ``x + ``" is "``); ` `    ``System.out.print(nextLargerElement(root, x).key + ``"\n"``); ` ` `  `} ` `} ` ` `  `// This code is contributed by 29AjayKumar `

## C#

 `// C# program to find next larger element ` `// in an n-ary tree. ` `using` `System; ` `using` `System.Collections.Generic; ` ` `  `class` `GFG ` `{ ` ` `  `// Structure of a node of an n-ary tree ` `class` `Node ` `{ ` `    ``public` `int` `key; ` `    ``public` `List child; ` `}; ` `static` `Node res; ` ` `  `// Utility function to create a new tree node ` `static` `Node newNode(``int` `key) ` `{ ` `    ``Node temp = ``new` `Node(); ` `    ``temp.key = key; ` `    ``temp.child = ``new` `List(); ` `    ``return` `temp; ` `} ` ` `  `static` `void` `nextLargerElementUtil(Node root,  ` `                                  ``int` `x) ` `{ ` `    ``if` `(root == ``null``) ` `        ``return``; ` ` `  `    ``// if root is less than res but  ` `    ``// greater than x, update res ` `    ``if` `(root.key > x)  ` `        ``if` `((res == ``null` `||  ` `            ``(res).key > root.key)) ` `            ``res = root;  ` ` `  `    ``// Number of children of root ` `    ``int` `numChildren = root.child.Count; ` ` `  `    ``// Recur calling for every child ` `    ``for` `(``int` `i = 0; i < numChildren; i++) ` `        ``nextLargerElementUtil(root.child[i], x); ` ` `  `    ``return``; ` `} ` ` `  `// Function to find next Greater element  ` `// of x in tree ` `static` `Node nextLargerElement(Node root,     ` `                                  ``int` `x) ` `{ ` `    ``// resultant node ` `    ``res = ``null``; ` ` `  `    ``// calling helper function ` `    ``nextLargerElementUtil(root, x); ` ` `  `    ``return` `res; ` `} ` ` `  `// Driver Code ` `public` `static` `void` `Main(String[] args) ` `{ ` `    ``/* Let us create below tree ` `    ``*             5 ` `    ``*         / | \ ` `    ``*         1 2 3 ` `    ``*     / / \ \ ` `    ``*     15 4 5 6 ` `    ``*/` `    ``Node root = newNode(5); ` `    ``(root.child).Add(newNode(1)); ` `    ``(root.child).Add(newNode(2)); ` `    ``(root.child).Add(newNode(3)); ` `    ``(root.child[0].child).Add(newNode(15)); ` `    ``(root.child[1].child).Add(newNode(4)); ` `    ``(root.child[1].child).Add(newNode(5)); ` `    ``(root.child[2].child).Add(newNode(6)); ` ` `  `    ``int` `x = 5; ` ` `  `    ``Console.Write(``"Next larger element of "` `+ ` `                                 ``x + ``" is "``); ` `    ``Console.Write(nextLargerElement(root, x).key + ``"\n"``); ` `} ` `} ` ` `  `// This code is contributed by PrinciRaj1992 `

Output:

```Next larger element of 5 is 6
```

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