Swap_Nodes_in_Pairs.cpp

18_Swap_Nodes_in_Pairs.cpp

@@ -0,0 +1,42 @@
+#include <bits/stdc++.h>
+using namespace std;
+using lli = long long int;
+using ll = long long;
+#define endl '\n'
+
+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* p=head;
+        ListNode* k=new ListNode(0);
+        ListNode* prev=k;
+        prev->next=head;
+        while(p!=NULL && p->next!=NULL){
+            ListNode* q=p->next;
+            prev->next=q;
+            p->next=q->next;
+            q->next=p;
+            prev=p;
+            p=p->next; 
+        }
+        return k->next;
+    }
+};
+
+int main()
+{
+    ios_base::sync_with_stdio(false);
+    cin.tie(0);
+
+    return 0;
+}