From 03895fff09c7633f07bc3863a20aecd0e3438bb0 Mon Sep 17 00:00:00 2001
From: ShashankZobb <shashanknke1112@gmail.com>
Date: Fri, 9 Dec 2022 22:05:04 +0530
Subject: [PATCH] Solution for Reverse in K group problem

---
 Reverse in K group/reverse_in_k_group.cpp | 90 +++++++++++++++++++++++
 1 file changed, 90 insertions(+)
 create mode 100644 Reverse in K group/reverse_in_k_group.cpp

diff --git a/Reverse in K group/reverse_in_k_group.cpp b/Reverse in K group/reverse_in_k_group.cpp
new file mode 100644
index 00000000..f7a7827d
--- /dev/null
+++ b/Reverse in K group/reverse_in_k_group.cpp	
@@ -0,0 +1,90 @@
+#include<bits/stdc++.h>
+using namespace std;
+class ListNode{
+public:
+    int val;
+    ListNode *next;
+    ListNode(int data = 0, ListNode *next_node = NULL){
+        val = data;
+        next = next_node;
+    }
+};
+ListNode* reverseKGroup(ListNode* head, int k) {
+    if(k == 0)return head;
+    ListNode *cur = head, *prev = NULL;
+    while(cur != NULL){
+        int num_of_node_passed = 0;
+        ListNode *temp1 = prev; // tail of previous group
+        ListNode *temp2 = cur; //will become the tail of current group after reversing the group
+        num_of_node_passed = 0;
+        ListNode *temp = cur;
+        while(temp != NULL && num_of_node_passed < k){
+            num_of_node_passed++;
+            temp = temp->next;
+        }
+        if(num_of_node_passed < k)break; // Not enough node to make a group
+        num_of_node_passed = 0;
+        while(cur != NULL && num_of_node_passed < k){
+            ListNode *next_node = cur->next;
+            cur->next = prev;
+            prev = cur;
+            cur = next_node;
+            num_of_node_passed++;
+        }
+        if(temp1 != NULL){
+            temp1->next = prev;
+        }
+        else{
+            head = prev;
+        }
+        temp2->next = cur;
+        prev = temp2;
+    }
+    return head;
+}
+ListNode *create_list(){
+    int length;
+    while(true){
+        cout << "Enter the length of linked list you wish to create: ";
+        cin >> length;
+        if(length < 0){
+            cout << "Please enter a positive number\n";
+        }
+        else{
+            break;
+        }
+    }
+    ListNode *dummy = new ListNode();
+    ListNode *tail = dummy;
+    cout << "Enter " << length << " integers for the linked list: ";
+    for(int i=0;i<length;i++){
+        int data;
+        cin >> data;
+        ListNode *new_node = new ListNode(data);
+        tail->next = new_node;
+        tail = tail->next;
+    }
+    return dummy->next;
+}
+int main(){
+    ListNode *head = create_list();
+    int k;
+    while(true){
+        cout << "Enter the value of k: ";
+        cin >> k;
+        if(k <= 0){
+            cout << "Please enter a number greater than 0\n";
+        }
+        else{
+            break;
+        }
+    }
+    head = reverseKGroup(head, k);
+    cout << "Output: ";
+    while(head != NULL){
+        cout << head->val << "->";
+        head = head->next;
+    }
+    cout << "NULL";
+    return 0;
+}