🚀 21-Jul-2020

Author: sureshmangs

competitive programming/leetcode/2020-July-Challenge/Day-20-Remove Linked List Elements.cpp

@@ -0,0 +1,56 @@
+Remove all elements from a linked list of integers that have value val.
+
+Example:
+
+Input:  1->2->6->3->4->5->6, val = 6
+Output: 1->2->3->4->5
+
+
+
+
+
+/**
+ * Definition for singly-linked list.
+ * struct ListNode {
+ *     int val;
+ *     ListNode *next;
+ *     ListNode() : val(0), next(nullptr) {}
+ *     ListNode(int x) : val(x), next(nullptr) {}
+ *     ListNode(int x, ListNode *next) : val(x), next(next) {}
+ * };
+ */
+class Solution {
+public:
+    ListNode* removeElements(ListNode* head, int val) {
+        if(!head) return head;
+        while(head->val==val && head->next!=NULL){
+            ListNode* tmp=head;
+            head=head->next;
+            delete tmp;
+        }
+        if(head->val==val){
+            // last node
+            delete head;
+            head=NULL;
+            return head;
+        }
+        ListNode *curr=head, *prev=head;
+        while(curr->next!=NULL){
+            if(curr->val==val){
+                prev->next=curr->next;
+                delete curr;
+                curr=prev->next;
+            } else {
+                prev=curr;
+                curr=curr->next;
+            }
+        }
+        // last node
+        if(curr->val==val){
+            prev->next=NULL;
+            delete curr;
+
+        }
+        return head;
+    }
+};

competitive programming/leetcode/203. Remove Linked List Elements.cpp

@@ -0,0 +1,56 @@
+Remove all elements from a linked list of integers that have value val.
+
+Example:
+
+Input:  1->2->6->3->4->5->6, val = 6
+Output: 1->2->3->4->5
+
+
+
+
+
+/**
+ * Definition for singly-linked list.
+ * struct ListNode {
+ *     int val;
+ *     ListNode *next;
+ *     ListNode() : val(0), next(nullptr) {}
+ *     ListNode(int x) : val(x), next(nullptr) {}
+ *     ListNode(int x, ListNode *next) : val(x), next(next) {}
+ * };
+ */
+class Solution {
+public:
+    ListNode* removeElements(ListNode* head, int val) {
+        if(!head) return head;
+        while(head->val==val && head->next!=NULL){
+            ListNode* tmp=head;
+            head=head->next;
+            delete tmp;
+        }
+        if(head->val==val){
+            // last node
+            delete head;
+            head=NULL;
+            return head;
+        }
+        ListNode *curr=head, *prev=head;
+        while(curr->next!=NULL){
+            if(curr->val==val){
+                prev->next=curr->next;
+                delete curr;
+                curr=prev->next;
+            } else {
+                prev=curr;
+                curr=curr->next;
+            }
+        }
+        // last node
+        if(curr->val==val){
+            prev->next=NULL;
+            delete curr;
+
+        }
+        return head;
+    }
+};