Linked List

Author: Mohit Jain

DpIntro

@@ -0,0 +1,46 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int lastIndex(int a[], int n, int m){
+
+	if (n == 0) return -1;
+
+	int lIndex = lastIndex(a+1,n-1,m);
+
+	if(lIndex == -1) {
+		if(a[0] == m ) {
+			return 0;
+		}
+		else return -1;
+	}
+
+	return lIndex + 1;
+}
+
+
+int main() {
+
+
+     #ifndef ONLINE_JUDGE
+    // for getting input from input.txt
+    freopen("input.txt", "r", stdin);
+    // for writing output to output.txt
+    freopen("output.txt", "w", stdout);
+    #endif
+
+    int n; 
+
+    cin>>n;
+
+    int a[n];
+
+    for(int i =0 ; i < n ; i++) {
+    	cin>>a[i];
+    }
+
+    int m; cin >> m;
+     cout<<lastIndex(a,n,m);
+
+     return 0;
+}

DpIntro.cpp

@@ -0,0 +1,283 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+class node{
+public: 
+	int data;
+	node *next;
+
+	node(int d){
+		data = d;
+		next = NULL;
+	}
+};
+
+// Linked Class  (OOP)
+
+// class LinkedList {
+// 	node *head;
+// 	node *tail;
+
+// public:
+// 	LinkedList(){
+
+// 	}
+// 	void insert(int d)
+// }
+
+void build() {
+
+}
+
+void insertAtHead(node*&head,int d) {
+   if(head == NULL) {
+   	head = new node(d);
+   	return;
+   }
+   node *n = new node(d);
+   n->next = head;
+   head = n;
+
+}
+int length(node*head){
+	int cnt =0;
+	while(head!= NULL) {
+		// cout<<head->data<<"- >";
+		head = head->next;
+	   cnt++;
+	}
+	return cnt;
+}
+void insertAtTail(node*&head,int data) {
+	if(head == NULL){
+		head = new node(data);
+		return;
+	}
+
+	node *tail = head;
+	while(tail->next != NULL){
+		tail = tail->next;
+	}
+	tail->next = new node(data);
+	return;
+}
+void insertInMiddle(node*&head,int data,int p){
+	if(head == NULL or p==0){
+		insertAtHead(head,data);
+	}
+	else if(p>length(head)){
+		insertAtTail(head,data);
+	}
+	else {
+		int jump = 1;
+		node *temp = head;
+
+		while(jump <= p-1) {
+			temp = temp->next;
+			jump++;
+		}
+		node * n = new node(data);
+		n-> next = temp->next;
+		temp->next = n;
+	}
+}
+void print(node*head){
+	while(head!= NULL) {
+		cout<<head->data<<"- >";
+		head = head->next;
+	}
+}
+void deleteHead(node*&head){
+	if(head == NULL){
+		return;
+	}
+	node *temp = head->next;
+	delete head;
+	head = temp;
+	
+}
+bool search(node *head,int key){
+	node*temp = head;
+
+	while(temp!= NULL){
+		if(head->data == key) return true;
+
+		head = head-> next;
+	}
+	return false;
+}
+// recursively 
+bool searchRecursive(node*head,int key) {
+	if(head == NULL) return false;
+
+	if(head->data==key){
+		return true;
+	} else {
+		return searchRecursive(head->next,key);
+	}
+}
+
+node* take_input_2(){
+   int d;
+   cin>>d;
+    node*head = NULL;
+   while(d!=-1){
+     insertAtHead(head,d);
+     cin>>d;
+   }
+   return head;
+}
+ostream& operator<<(ostream &os,node*head){
+	print(head);
+    return os;
+}
+
+istream& operator>>(istream &is,node*&head){
+	head = take_input_2();
+	return is;
+}
+
+void reverse(node*&head) {
+	node*C = head;
+	node* P = NULL;
+
+	node*N;
+
+	while(C!= NULL){
+
+		N = C->next;
+
+		C->next=P;
+
+		P = C;
+		C = N;
+	}
+	head = P;
+}
+
+// recursively reverse a linked list
+
+node* recReverse(node*head){
+    if(head->next == NULL or head==NULL){
+    	return head;
+    }
+   
+   node* shead = recReverse(head->next);
+
+   node *temp = head->next;
+   head->next = NULL;
+   temp->next = head;
+  
+   return shead;
+
+
+
+}
+   node* midpoint(node*head){
+   	if(head==NULL or head->next == NULL){
+   		return head;
+   	}
+   	node*slow = head;
+   	node*fast = head-> next;
+
+   	while(fast->next!=NULL and fast!=NULL) {
+   		fast = fast->next->next;
+   		slow = slow->next;
+   	}
+   
+      return slow;
+   }
+   node* kthPositionFromEnd(node *head, int k){
+   	if(head ==NULL or head->next == NULL) 
+   		return head;
+
+   	node* slow = head;
+   	node* fast = head;
+   while(k!=0){
+   	 fast = fast->next;
+   }
+   while(fast!=NULL and fast->next!= NULL){
+   	slow = slow->next;
+   	fast = fast->next;
+   }
+
+    return slow;
+
+   }
+node* merge(node*a,node*b){
+
+   	if(a==NULL) return b;
+
+   	if(b==NULL) return a;
+
+   	node*c;
+    if(a->data < b->data){
+    	c = a;
+    	c->next = merge(a->next,b);
+    } else {
+    	c = b;
+    	c->next = merge(a,b->next);
+    }
+    return c;
+}
+// merge sort on linked list
+node* mergeSort(node *head) {
+	if(head==NULL or head->next==NULL) return head;
+
+	node* mid = midpoint(head);
+	node* b = mid->next;
+    node* a = head;
+
+    mid->next = NULL;
+
+    a = mergeSort(a);
+    b = mergeSort(b);
+
+    node* c = merge(a,b);
+
+    return c;
+
+}
+// Cycle detection and removal (Floyd's cycle)
+bool detectCycle(node* head) {
+	node*slow = head;
+	node*fast = head;
+
+	while(fast!=NULL && fast->next!=NULL){
+		fast = fast->next->next;
+		slow = slow->next;
+		if(fast==slow) return true;
+
+	}
+
+	return false;
+
+}
+
+
+int main() {
+    
+    #ifndef ONLINE_JUDGE
+    // for getting input from input.txt
+    freopen("input.txt", "r", stdin);
+    // for writing output to output.txt
+    freopen("output.txt", "w", stdout);
+    #endif
+    
+	node*head = take_input_2();
+    node*head2 = take_input_2();
+    node *head,*head2;
+    cin>>head>>head2;
+	cout<<head;
+	cout<<head2;
+	cout<<head<<head2;
+    // insertAtHead(head,3);
+    // insertAtHead(head,2);
+    // insertAtHead(head,1);
+    // insertAtHead(head,3);
+    // insertInMiddle(head,5,2);
+
+     // print(head);
+
+}

LastIndex

@@ -0,0 +1,54 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+class node{
+public: 
+	int data;
+	node *next;
+
+	node(int d){
+		data = d;
+		next = NULL;
+	}
+};
+
+void insert(node*&head,int data){
+
+	 node* n = new node(data);
+
+	 node*temp = head;
+
+	 n->next = head;
+	 if(temp!= NULL){
+
+		while(temp->next!= head){
+		
+			temp = temp->next;
+		
+		}
+		temp->next = n;
+
+
+	}else {
+		n->next = n;
+	}
+	head = n;
+
+}
+void print(node*head){
+	node*teamp = head;
+	while(temp->next!= head){
+		cout<<temp->data<<" ";
+		temp = temp->next;
+	}
+	cout<<temp->data<<endl;
+	return;
+}
+// deletion in circular Linked list 
+int main() {
+  
+
+
+	return 0;
+}

LastIndex.cpp

@@ -1 +1,3 @@
-4
+7
+86 -16 77 65 45 77 28
+77