swap two nodes in linked list

1//not changing the data inside
2//Try on your own first
3#include<iostream>
4using namespace std;
5struct node
6{
7  int data;
8  node* next;
9};
10node * head=NULL;
11void insertion(int key)
12{
13  node *temp=new node;
14  temp->data=key;
15  temp->next=NULL;
16  if(head==NULL)
17  {
18    head=temp;
19  }
20  else
21  {
22    node* ptr=head;
23    while(ptr->next!=NULL)
24    {
25      ptr=ptr->next;
26    }
27    ptr->next=temp;
28  }
29}
30void swapnode(int x,int y)
31{
32  if(x==y)
33  {
34    return;
35  }
36  node *x_prev=NULL;
37  node* x_curr=head;
38  node* y_prev=NULL;
39  node* y_curr=head;
40  while(x_curr!=NULL&&x_curr->data!=x)
41  {
42    x_prev=x_curr;
43    x_curr=x_curr->next;
44  }
45  while(y_curr!=NULL&&y_curr->data!=y)
46  {
47    y_prev=y_curr;
48    y_curr=y_curr->next;
49  }
50  if(x_curr==NULL||y_curr==NULL)
51  {
52    return;
53  }
54  if(x_prev!=NULL)
55  {
56    x_prev->next=y_curr;
57  }
58  else
59  {
60    head=y_curr;
61  }
62  if(y_prev!=NULL)
63  {
64    y_prev->next=x_curr;
65  }
66  else
67  {
68    head=x_curr;
69  }
70  node *temp=y_curr->next;
71  y_curr->next=x_curr->next;
72  x_curr->next=temp;
73}
74void print()
75{
76  node* temp=head;
77  while(temp!=NULL)
78  {
79    cout<<temp->data<<" ";
80    temp=temp->next;
81  }
82}
83int main()
84{
85  int n;
86  cin>>n;
87  int value;
88  for(int i=0;i<n;i++)
89  {
90    cin>>value;
91    insertion(value);
92  }
93  int p,q;
94  cin>>p>>q;
95  swapnode(p,q);
96  print();
97  return 0;
98}
99