feat: 24_feat_nodes_in_pairs

24_swap_nodes_in_pairs/main.cpp

@@ -0,0 +1,55 @@
+#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) {}
+};
+
+class Solution {
+   public:
+    ListNode* swapPairs(ListNode* head) {
+        ListNode* currentNode = head;
+        ListNode* lastNode = nullptr;
+        ListNode* lastLastNode = nullptr;
+
+        int count = 0;
+        while (currentNode != nullptr) {
+            if (count % 2 == 1) {
+                ListNode* nextNode = currentNode->next;
+                currentNode->next = lastNode;
+                lastNode->next = nextNode;
+
+                if (count / 2 == 0) {
+                    head = currentNode;
+                } else {
+                    lastLastNode->next = currentNode;
+                }
+                
+                lastLastNode = currentNode;
+                currentNode = nextNode;
+            } else {
+                lastLastNode = lastNode;
+                lastNode = currentNode;
+                currentNode = currentNode->next;
+            }
+            count++;
+        }
+
+        return head;
+    }
+};
+
+int main() {
+    ListNode* head = new ListNode(1);
+    ListNode* currentNode = head;
+    for (int i = 1; i < 4; i++) {
+        currentNode->next = new ListNode(i + 1);
+        currentNode = currentNode->next;
+    }
+    Solution().swapPairs(head);
+    return 0;
+}