GEEKS FOR GEEKS SOLUTIONS🫢

24 th july || c++

class Solution { public: vector v_v; //Function to return list containing elements of right view of binary tree. void Right_View(vector &v_v, int k, Node * root) { if(root == NULL) { return; } if(v_v.size() == k) { v_v.push_back(root->data); } Right_View(v_v, k + 1, root->right); Right_View(v_v, k + 1, root->left); } vector rightView(Node *root) { // Your Code here Right_View(v_v, 0, root); return v_v; } };

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23 july || c++

class Solution { public: //Function to sort a linked list of 0s, 1s and 2s. Node* segregate(Node *head) { // Add code here if(head == NULL || head ->next == NULL) return head; Node *temp = NULL; Node *slow = head; Node *fast = head; // 2 pointer appraoach / turtle-hare Algorithm (Finding the middle element) while(fast != NULL && fast -> next != NULL) { temp = slow; slow = slow->next; //slow increment by 1 fast = fast ->next ->next; //fast incremented by 2 } temp -> next = NULL; //end of first left half Node* l1 = segregate(head); //left half recursive call Node* l2 = segregate(slow); //right half recursive call return mergelist(l1, l2); //mergelist Function call } //MergeSort Function O(n*logn) Node* mergelist(Node *l1, Node *l2) { Node *ptr = new Node(0); Node *curr = ptr; while(l1 != NULL && l2 != NULL) { if(l1->data <= l2->data) { curr -> next = l1; l1 = l1 -> next; } else { curr -> next = l2; l2 = l2 -> next; } curr = curr ->next; } //for unqual length linked list if(l1 != NULL) { curr -> next = l1; l1 = l1->next; } if(l2 != NULL) { curr -> next = l2; l2 = l2 ->next; } return ptr->next; } };

22 july || c++

class Solution { public: //Function to remove duplicates from unsorted linked list. Node * removeDuplicates( Node *head) { if(head==NULL) return NULL; Node* curr=head; unordered_map mp; Node* anshead=NULL; Node* anscurr=NULL; while(curr!=NULL){ mp[curr->data]++; if(mp[curr->data]<=1){ Node* newNode=new Node(curr->data); if(anshead==NULL){ anshead=newNode; anscurr=newNode; }else{ anscurr->next=newNode; anscurr=newNode; } } curr=curr->next; } return anshead; } };

20 july ||c++

class Solution{ public: int solve(int i ,int j ,string s,string t,vector>&dp){ if(i<0 or j<0 )return 0; if(dp[i][j]!=-1)return dp[i][j]; int match=0; if(s[i]==t[j])match=1+solve(i-1,j-1,s,t,dp); int nomatch=max(solve(i-1,j,s,t,dp),solve(i,j-1,s,t,dp)); return dp[i][j]=max(nomatch,match); } int longestPalinSubseq(string A) { string t=A; reverse(t.begin(),t.end()); // vector>dp(A.size()+1,(vector(A.size()+1,0))); int n=A.size(); vectorprev(n+1,0),cur(n+1,0); for(int i=1;i<=n;i++){ for(int j=1;j<=n;j++){ if(A[i-1]==t[j-1])cur[j]=1+prev[j-1]; else cur[j]=max(prev[j],cur[j-1]); } prev=cur; } return prev[n]; } };

18 july || c++

class Solution { public: int LongestRepeatingSubsequence(string str){ int n = str.length(); int dp[n+1][n+1]; for (int i=0; i<=n; i++) for (int j=0; j<=n; j++) dp[i][j] = 0; for (int i=1; i<=n; i++) { for (int j=1; j<=n; j++) { if (str[i-1] == str[j-1] && i != j) dp[i][j] = 1 + dp[i-1][j-1]; else dp[i][j] = max(dp[i][j-1], dp[i-1][j]); } } return dp[n][n]; } };

17 th july || c++

class Solution { public: string FirstNonRepeating(string A){ unordered_map mp; queue q; string ans=""; for(char c: A){ //1 increment the freq mp[c]++; if(mp[c]==1){ q.push(c); } //2 remove repeating element while(!q.empty() && mp[q.front()]>1){ q.pop(); } //3 store the element if(q.empty()){ ans+='#'; }else{ ans+=q.front(); } } return ans; } };

16 th july || c++

class Solution { public: //Function to delete middle element of a stack. void deleteMid(stack<int>&s, int si) { int i=0; int n=si/2; stack<int>s1; while(i<n) { int a=s.top(); s.pop(); s1.push(a); i++; } s.pop(); while(!s1.empty()) { int a=s1.top();s1.pop(); s.push(a); } } };