add q24 java, cpp, go

Author: godcrampy

24-swap-nodes-in-pairs/cpp/main.cpp

@@ -0,0 +1,32 @@
+/**
+ * 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* swapPairs(ListNode* head) {
+    if (head == NULL || head->next == NULL) {
+      return head;
+    }
+
+    ListNode* d = new ListNode(0, head);
+    ListNode* a = d;
+    ListNode* b = d->next;
+
+    while (b != NULL && b->next != NULL) {
+      a->next = b->next;
+      b->next = a->next->next;
+      a->next->next = b;
+      b = b->next;
+      a = a->next->next;
+    }
+
+    return d->next;
+  }
+};

24-swap-nodes-in-pairs/go/main.go

@@ -0,0 +1,28 @@
+package main
+
+/**
+ * Definition for singly-linked list.
+ * type ListNode struct {
+ *     Val int
+ *     Next *ListNode
+ * }
+ */
+func swapPairs(head *ListNode) *ListNode {
+	if head == nil || head.Next == nil {
+		return head
+	}
+
+	d := &ListNode{Val: 0, Next: head}
+	a := d
+	b := d.Next
+
+	for b != nil && b.Next != nil {
+		a.Next = b.Next
+		b.Next = a.Next.Next
+		a.Next.Next = b
+		a = a.Next.Next
+		b = b.Next
+	}
+
+	return d.Next
+}

24-swap-nodes-in-pairs/java/Solution.java

@@ -0,0 +1,26 @@
+/**
+ * Definition for singly-linked list. public class ListNode { int val; ListNode next; ListNode() {}
+ * ListNode(int val) { this.val = val; } ListNode(int val, ListNode next) { this.val = val;
+ * this.next = next; } }
+ */
+class Solution {
+  public ListNode swapPairs(ListNode head) {
+    if (head == null || head.next == null) {
+      return head;
+    }
+    ListNode d = new ListNode();
+    d.next = head;
+    ListNode a = d;
+    ListNode b = d.next;
+
+    while (b != null && b.next != null) {
+      a.next = b.next;
+      b.next = a.next.next;
+      a.next.next = b;
+      a = a.next.next;
+      b = b.next;
+    }
+
+    return d.next;
+  }
+}