added few linked list solution

Author: marcustut

leetcode/linked_list/middle_of_the_linked_list/main.cpp

@@ -0,0 +1,48 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+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) {}
+};
+
+ListNode* middleNode(ListNode* head) {
+  ListNode* slow = head;
+  ListNode* fast = head;
+
+  while (fast != nullptr && fast->next != nullptr) {
+    slow = slow->next;
+    fast = fast->next->next;
+  }
+
+  return slow;
+}
+
+struct testcase {
+  ListNode* head;
+  ListNode* expected;
+};
+
+void test() {
+  vector<testcase> testcases{
+    (testcase) {new ListNode(1, new ListNode(1, new ListNode(2))), new ListNode(1, new ListNode(2))},
+    (testcase) {new ListNode(1, new ListNode(1, new ListNode(2, new ListNode(3, new ListNode(3))))), new ListNode(1, new ListNode(2, new ListNode(3)))},
+  };
+  for (int i = 0; i < testcases.size(); i++) {
+    ListNode* result = deleteDuplicates(testcases[i].head);
+    while (result != NULL) {
+      assert(testcases[i].expected->val == result->val);
+      result = result->next;
+      testcases[i].expected = testcases[i].expected->next;
+    }
+    cout << "test" << i + 1 << ": PASSED\n";
+  }
+}
+
+int main() {
+  test();
+}

leetcode/linked_list/middle_of_the_linked_list/main.rs

@@ -0,0 +1,42 @@
+// Definition for singly-linked list.
+// #[derive(PartialEq, Eq, Clone, Debug)]
+// pub struct ListNode {
+//   pub val: i32,
+//   pub next: Option<Box<ListNode>>
+// }
+// 
+// impl ListNode {
+//   #[inline]
+//   fn new(val: i32) -> Self {
+//     ListNode {
+//       next: None,
+//       val
+//     }
+//   }
+// }
+impl Solution {
+    pub fn middle_node(head: Option<Box<ListNode>>) -> Option<Box<ListNode>> {
+        let mut cursor = head.clone().unwrap();
+        let mut count: usize = 0;
+
+        while cursor.next != None {
+            count += 1;
+            cursor = cursor.next.unwrap();
+        }
+
+        let mut mid = if count % 2 == 0 {
+            count / 2
+        } else {
+            (count / 2) + 1
+        };
+
+        let mut new_cursor = head.unwrap();
+
+        while mid != 0 {
+            mid -= 1;
+            new_cursor = new_cursor.next.unwrap();
+        }
+
+        Some(new_cursor)
+    }
+}

leetcode/linked_list/remove_duplicates_from_sorted_list/main.cpp

@@ -0,0 +1,57 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+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) {}
+};
+
+ListNode* deleteDuplicates(ListNode* head) {
+  ListNode* curr = head;
+
+  // exit when pointing at NULL
+  while (curr != nullptr) {
+    // [next elem is not NULL] and [curr elem is equals to next elem]
+    while (curr->next != nullptr && curr->val == curr->next->val) {
+      curr->next = curr->next->next;
+    }
+    // move to next elem
+    curr = curr->next;
+  }
+
+  return head;
+}
+
+struct testcase {
+  ListNode* head;
+  ListNode* expected;
+};
+
+void test() {
+  vector<testcase> testcases{
+    // [1,1,2] [1,2]
+    (testcase) {new ListNode(1, new ListNode(1, new ListNode(2))), new ListNode(1, new ListNode(2))}, 
+    // [1,1,2,3,3] [1,2,3]
+    (testcase) {new ListNode(1, new ListNode(1, new ListNode(2, new ListNode(3, new ListNode(3))))), new ListNode(1, new ListNode(2, new ListNode(3)))},
+    // [1,1,1] [1]
+    (testcase) {new ListNode(1, new ListNode(1, new ListNode(1))), new ListNode(1)}, 
+  };
+  for (int i = 0; i < testcases.size(); i++) {
+    ListNode* result = deleteDuplicates(testcases[i].head);
+    while (result != NULL) {
+      assert(testcases[i].expected->val == result->val);
+      result = result->next;
+      testcases[i].expected = testcases[i].expected->next;
+    }
+    cout << "test" << i + 1 << ": PASSED\n";
+  }
+}
+
+int main() {
+  test();
+}
+

leetcode/linked_list/remove_nth_node_from_end_of_list/main.cpp

@@ -25,4 +25,4 @@ ListNode *removeNthFromEnd(ListNode *head, int n)
     slow->next = slow->next->next;
 
     return head;
-}
+}