Merge pull request div-bargali#615 from heri2468/patch-5

Flatten_List.cpp added

Author: div-bargali

C++/Data-Structures/LinkedList/Flatten_List.cpp

@@ -0,0 +1,149 @@
+/*
+Given a Linked List of size N, where every node represents a linked list and contains two pointers of its type:
+(i) a next pointer to the next node,
+(ii) a bottom pointer to a linked list where this node is head.
+
+Note: The flattened list will be printed using the bottom pointer instead of next pointer.
+
+
+*/
+#include <bits/stdc++.h>
+using namespace std;
+
+struct Node{
+int data;
+struct Node * next;
+struct Node * bottom;
+
+Node(int x){
+ data = x;
+ next = NULL;
+ bottom = NULL;
+}
+
+};
+
+void printList(Node *Node)
+{
+ while (Node != NULL)
+ {
+ printf("%d ", Node->data);
+ Node = Node->bottom;
+ }
+}
+
+Node* flatten (Node* root); //function for flattening a multilevel linked list
+
+int main(void) {
+
+int t;
+cin>>t; // number of test cases
+while(t--){
+ int n,m,flag=1,flag1=1;
+ struct Node * temp=NULL;
+struct Node * head=NULL;
+struct Node * pre=NULL;
+struct Node * tempB=NULL;
+struct Node * preB=NULL;
+cin>>n;
+ int work[n];
+for(int i=0;i<n;i++)
+ cin>>work[i];
+for(int i=0;i<n;i++){
+m=work[i];
+--m;
+int data;
+scanf("%d",&data);
+temp = new Node(data);
+temp->next = NULL;
+temp->bottom = NULL;
+
+if(flag){
+head = temp;
+pre = temp;
+flag = 0;
+flag1 = 1;
+}
+else{
+pre->next = temp;
+pre = temp;
+flag1 = 1;
+}
+for(int j=0;j<m;j++){
+
+int temp_data;
+scanf("%d",&temp_data);
+tempB = new Node(temp_data);
+
+if(flag1){
+temp->bottom=tempB;
+preB=tempB;
+flag1=0;
+}
+else{
+preB->bottom=tempB;
+preB=tempB;
+}
+}
+}
+ Node *fun = head;
+ Node *fun2=head;
+
+ Node* root = flatten(head);
+ printList(root);
+ cout<<endl;
+
+}
+return 0;
+}
+// } Driver Code Ends
+
+
+/* Node structure used in the program
+
+struct Node{
+int data;
+struct Node * next;
+struct Node * bottom;
+
+Node(int x){
+ data = x;
+ next = NULL;
+ bottom = NULL;
+}
+
+};
+*/
+ 
+Node *merge(Node *a,Node *b)
+{
+ if(a==NULL)
+ return b;
+ if(b==NULL)
+ return a;
+ Node *result;
+ if(a->data<b->data)
+ {
+ result =a;
+ result->bottom = merge(a->bottom,b);
+ }
+ else
+ {
+ result=b;
+ result->bottom = merge(a,b->bottom);
+ }
+ return result;
+}
+/* Function which returns the root of 
+ the flattened linked list. */
+Node *flatten(Node *root)
+{
+ // Your code here
+ if(root==NULL||root->next==NULL) return root;
+ 
+ return merge(root,flatten(root->next));
+}
+
+/*
+Approach used is to merge the bottom node with the current node.
+*/