C Program to concatenate two circular linked lists

Data Structure Linked List (Article) Linked List (Program)

1085

Program:

<span class="com">/*  C Program to concatenate two circular linked lists*/</span><span class="pln">
</span><span class="com">#include</span><span class="str">&lt;stdio.h&gt;</span><span class="pln">
</span><span class="com">#include</span><span class="str">&lt;stdlib.h&gt;</span><span class="pln">

</span><span class="kwd">struct</span><span class="pln"> node
</span><span class="pun">{</span><span class="pln">
	</span><span class="kwd">int</span><span class="pln"> info</span><span class="pun">;</span><span class="pln">
	</span><span class="kwd">struct</span><span class="pln"> node </span><span class="pun">*</span><span class="pln">link</span><span class="pun">;</span><span class="pln">
</span><span class="pun">};</span><span class="pln">

</span><span class="kwd">struct</span><span class="pln"> node </span><span class="pun">*</span><span class="pln">create_list</span><span class="pun">(</span><span class="kwd">struct</span><span class="pln"> node </span><span class="pun">*</span><span class="kwd">last</span><span class="pun">);</span><span class="pln">
</span><span class="kwd">void</span><span class="pln"> display</span><span class="pun">(</span><span class="kwd">struct</span><span class="pln"> node </span><span class="pun">*</span><span class="kwd">last</span><span class="pun">);</span><span class="pln">
</span><span class="kwd">struct</span><span class="pln"> node </span><span class="pun">*</span><span class="pln">addtoempty</span><span class="pun">(</span><span class="kwd">struct</span><span class="pln"> node </span><span class="pun">*</span><span class="kwd">last</span><span class="pun">,</span><span class="kwd">int</span><span class="pln"> data </span><span class="pun">);</span><span class="pln">
</span><span class="kwd">struct</span><span class="pln"> node </span><span class="pun">*</span><span class="pln">addatend</span><span class="pun">(</span><span class="kwd">struct</span><span class="pln"> node </span><span class="pun">*</span><span class="kwd">last</span><span class="pun">,</span><span class="kwd">int</span><span class="pln"> data</span><span class="pun">);</span><span class="pln">
</span><span class="kwd">struct</span><span class="pln"> node </span><span class="pun">*</span><span class="pln">concat</span><span class="pun">(</span><span class="kwd">struct</span><span class="pln"> node </span><span class="pun">*</span><span class="pln">last1</span><span class="pun">,</span><span class="kwd">struct</span><span class="pln"> node </span><span class="pun">*</span><span class="pln">last2</span><span class="pun">);</span><span class="pln">

main</span><span class="pun">(</span><span class="pln"> </span><span class="pun">)</span><span class="pln">
</span><span class="pun">{</span><span class="pln">
	</span><span class="kwd">struct</span><span class="pln"> node </span><span class="pun">*</span><span class="pln">last1</span><span class="pun">=</span><span class="pln">NULL</span><span class="pun">,*</span><span class="pln">last2</span><span class="pun">=</span><span class="pln">NULL</span><span class="pun">;</span><span class="pln">
	last1</span><span class="pun">=</span><span class="pln">create_list</span><span class="pun">(</span><span class="pln">last1</span><span class="pun">);</span><span class="pln">
	last2</span><span class="pun">=</span><span class="pln">create_list</span><span class="pun">(</span><span class="pln">last2</span><span class="pun">);</span><span class="pln">
	printf</span><span class="pun">(</span><span class="str">"First list is :  "</span><span class="pun">);</span><span class="pln">
	display</span><span class="pun">(</span><span class="pln">last1</span><span class="pun">);</span><span class="pln">
	printf</span><span class="pun">(</span><span class="str">"Second list is :  "</span><span class="pun">);</span><span class="pln">
	display</span><span class="pun">(</span><span class="pln">last2</span><span class="pun">);</span><span class="pln">
    last1</span><span class="pun">=</span><span class="pln">concat</span><span class="pun">(</span><span class="pln">last1</span><span class="pun">,</span><span class="pln"> last2</span><span class="pun">);</span><span class="pln">
	printf</span><span class="pun">(</span><span class="str">"Concatenated list is  : "</span><span class="pun">);</span><span class="pln">
	display</span><span class="pun">(</span><span class="pln">last1</span><span class="pun">);</span><span class="pln">
</span><span class="pun">}</span><span class="com">/*End of main( )*/</span><span class="pln">

</span><span class="kwd">struct</span><span class="pln"> node </span><span class="pun">*</span><span class="pln">concat</span><span class="pun">(</span><span class="pln"> </span><span class="kwd">struct</span><span class="pln"> node </span><span class="pun">*</span><span class="pln">last1</span><span class="pun">,</span><span class="kwd">struct</span><span class="pln"> node </span><span class="pun">*</span><span class="pln">last2</span><span class="pun">)</span><span class="pln">
</span><span class="pun">{</span><span class="pln">
	</span><span class="kwd">struct</span><span class="pln"> node </span><span class="pun">*</span><span class="pln">ptr</span><span class="pun">;</span><span class="pln">
	</span><span class="kwd">if</span><span class="pun">(</span><span class="pln">last1</span><span class="pun">==</span><span class="pln">NULL</span><span class="pun">)</span><span class="pln">
	</span><span class="pun">{</span><span class="pln">
		last1</span><span class="pun">=</span><span class="pln">last2</span><span class="pun">;</span><span class="pln">
		</span><span class="kwd">return</span><span class="pln"> last1</span><span class="pun">;</span><span class="pln">
	</span><span class="pun">}</span><span class="pln">
	</span><span class="kwd">if</span><span class="pun">(</span><span class="pln">last2</span><span class="pun">==</span><span class="pln">NULL </span><span class="pun">)</span><span class="pln">   
		</span><span class="kwd">return</span><span class="pln"> last1</span><span class="pun">;</span><span class="pln">
	ptr</span><span class="pun">=</span><span class="pln">last1</span><span class="pun">-&gt;</span><span class="pln">link</span><span class="pun">;</span><span class="pln">
	last1</span><span class="pun">-&gt;</span><span class="pln">link</span><span class="pun">=</span><span class="pln">last2</span><span class="pun">-&gt;</span><span class="pln">link</span><span class="pun">;</span><span class="pln">
	last2</span><span class="pun">-&gt;</span><span class="pln">link</span><span class="pun">=</span><span class="pln">ptr</span><span class="pun">;</span><span class="pln">
	last1</span><span class="pun">=</span><span class="pln">last2</span><span class="pun">;</span><span class="pln">
	</span><span class="kwd">return</span><span class="pln"> last1</span><span class="pun">;</span><span class="pln">
</span><span class="pun">}</span><span class="pln">
</span><span class="kwd">struct</span><span class="pln"> node </span><span class="pun">*</span><span class="pln">create_list</span><span class="pun">(</span><span class="kwd">struct</span><span class="pln"> node </span><span class="pun">*</span><span class="kwd">last</span><span class="pun">)</span><span class="pln">
</span><span class="pun">{</span><span class="pln">
	</span><span class="kwd">int</span><span class="pln"> i</span><span class="pun">,</span><span class="pln">n</span><span class="pun">;</span><span class="pln">
	</span><span class="kwd">int</span><span class="pln"> data</span><span class="pun">;</span><span class="pln">
	printf</span><span class="pun">(</span><span class="str">"Enter the number of nodes : "</span><span class="pun">);</span><span class="pln">
	scanf</span><span class="pun">(</span><span class="str">"%d"</span><span class="pun">,&amp;</span><span class="pln">n</span><span class="pun">);</span><span class="pln">
	</span><span class="kwd">last</span><span class="pun">=</span><span class="pln">NULL</span><span class="pun">;</span><span class="pln">
	</span><span class="kwd">if</span><span class="pun">(</span><span class="pln">n</span><span class="pun">==</span><span class="lit">0</span><span class="pun">)</span><span class="pln">
		</span><span class="kwd">return</span><span class="pln"> </span><span class="kwd">last</span><span class="pun">;</span><span class="pln">
	printf</span><span class="pun">(</span><span class="str">"Enter the element to be inserted : "</span><span class="pun">);</span><span class="pln">
	scanf</span><span class="pun">(</span><span class="str">"%d"</span><span class="pun">,&amp;</span><span class="pln">data</span><span class="pun">);</span><span class="pln">
	</span><span class="kwd">last</span><span class="pun">=</span><span class="pln">addtoempty</span><span class="pun">(</span><span class="kwd">last</span><span class="pun">,</span><span class="pln">data</span><span class="pun">);</span><span class="pln">
		
	</span><span class="kwd">for</span><span class="pun">(</span><span class="pln">i</span><span class="pun">=</span><span class="lit">2</span><span class="pun">;</span><span class="pln">i</span><span class="pun">&lt;=</span><span class="pln">n</span><span class="pun">;</span><span class="pln">i</span><span class="pun">++)</span><span class="pln">
	</span><span class="pun">{</span><span class="pln">
		printf</span><span class="pun">(</span><span class="str">"Enter the element to be inserted : "</span><span class="pun">);</span><span class="pln">
		scanf</span><span class="pun">(</span><span class="str">"%d"</span><span class="pun">,&amp;</span><span class="pln">data</span><span class="pun">);</span><span class="pln">
		</span><span class="kwd">last</span><span class="pun">=</span><span class="pln">addatend</span><span class="pun">(</span><span class="kwd">last</span><span class="pun">,</span><span class="pln">data</span><span class="pun">);</span><span class="pln">	
	</span><span class="pun">}</span><span class="pln">
	</span><span class="kwd">return</span><span class="pln"> </span><span class="kwd">last</span><span class="pun">;</span><span class="pln">
</span><span class="pun">}</span><span class="pln">

</span><span class="kwd">void</span><span class="pln"> display</span><span class="pun">(</span><span class="kwd">struct</span><span class="pln"> node </span><span class="pun">*</span><span class="kwd">last</span><span class="pun">)</span><span class="pln">
</span><span class="pun">{</span><span class="pln">
	</span><span class="kwd">struct</span><span class="pln"> node </span><span class="pun">*</span><span class="pln">p</span><span class="pun">;</span><span class="pln">
	</span><span class="kwd">if</span><span class="pun">(</span><span class="kwd">last</span><span class="pun">==</span><span class="pln">NULL</span><span class="pun">)</span><span class="pln">
	</span><span class="pun">{</span><span class="pln">
		printf</span><span class="pun">(</span><span class="str">"List is empty\n"</span><span class="pun">);</span><span class="pln">
		</span><span class="kwd">return</span><span class="pun">;</span><span class="pln">
	</span><span class="pun">}</span><span class="pln">
	p</span><span class="pun">=</span><span class="kwd">last</span><span class="pun">-&gt;</span><span class="pln">link</span><span class="pun">;</span><span class="pln">  </span><span class="com">/*p points to first node*/</span><span class="pln">
	</span><span class="kwd">do</span><span class="pln"> 
	</span><span class="pun">{</span><span class="pln">
		printf</span><span class="pun">(</span><span class="str">"%d "</span><span class="pun">,</span><span class="pln"> p</span><span class="pun">-&gt;</span><span class="pln">info</span><span class="pun">);</span><span class="pln">
		p</span><span class="pun">=</span><span class="pln">p</span><span class="pun">-&gt;</span><span class="pln">link</span><span class="pun">;</span><span class="pln">
	</span><span class="pun">}</span><span class="kwd">while</span><span class="pun">(</span><span class="pln">p</span><span class="pun">!=</span><span class="kwd">last</span><span class="pun">-&gt;</span><span class="pln">link</span><span class="pun">);</span><span class="pln">
	printf</span><span class="pun">(</span><span class="str">"\n"</span><span class="pun">);</span><span class="pln">
</span><span class="pun">}</span><span class="com">/*End of display( )*/</span><span class="pln">

</span><span class="kwd">struct</span><span class="pln"> node </span><span class="pun">*</span><span class="pln">addtoempty</span><span class="pun">(</span><span class="kwd">struct</span><span class="pln"> node </span><span class="pun">*</span><span class="kwd">last</span><span class="pun">,</span><span class="kwd">int</span><span class="pln"> data</span><span class="pun">)</span><span class="pln">
</span><span class="pun">{</span><span class="pln">
	</span><span class="kwd">struct</span><span class="pln"> node </span><span class="pun">*</span><span class="pln">tmp</span><span class="pun">;</span><span class="pln">
	tmp </span><span class="pun">=</span><span class="pln"> </span><span class="pun">(</span><span class="kwd">struct</span><span class="pln"> node </span><span class="pun">*)</span><span class="pln">malloc</span><span class="pun">(</span><span class="kwd">sizeof</span><span class="pun">(</span><span class="kwd">struct</span><span class="pln"> node</span><span class="pun">));</span><span class="pln">
	tmp</span><span class="pun">-&gt;</span><span class="pln">info </span><span class="pun">=</span><span class="pln"> data</span><span class="pun">;</span><span class="pln">
	</span><span class="kwd">last</span><span class="pln"> </span><span class="pun">=</span><span class="pln"> tmp</span><span class="pun">;</span><span class="pln">
	</span><span class="kwd">last</span><span class="pun">-&gt;</span><span class="pln">link </span><span class="pun">=</span><span class="pln"> </span><span class="kwd">last</span><span class="pun">;</span><span class="pln">
	</span><span class="kwd">return</span><span class="pln"> </span><span class="kwd">last</span><span class="pun">;</span><span class="pln">
</span><span class="pun">}</span><span class="com">/*End of addtoempty( )*/</span><span class="pln">

</span><span class="kwd">struct</span><span class="pln"> node </span><span class="pun">*</span><span class="pln">addatend</span><span class="pun">(</span><span class="kwd">struct</span><span class="pln"> node </span><span class="pun">*</span><span class="kwd">last</span><span class="pun">,</span><span class="kwd">int</span><span class="pln"> data</span><span class="pun">)</span><span class="pln">
</span><span class="pun">{</span><span class="pln">
	</span><span class="kwd">struct</span><span class="pln"> node </span><span class="pun">*</span><span class="pln">tmp</span><span class="pun">;</span><span class="pln">
	tmp </span><span class="pun">=</span><span class="pln"> </span><span class="pun">(</span><span class="kwd">struct</span><span class="pln"> node </span><span class="pun">*)</span><span class="pln">malloc</span><span class="pun">(</span><span class="kwd">sizeof</span><span class="pun">(</span><span class="kwd">struct</span><span class="pln"> node</span><span class="pun">));</span><span class="pln">
	tmp</span><span class="pun">-&gt;</span><span class="pln">info </span><span class="pun">=</span><span class="pln"> data</span><span class="pun">;</span><span class="pln">
	tmp</span><span class="pun">-&gt;</span><span class="pln">link </span><span class="pun">=</span><span class="pln"> </span><span class="kwd">last</span><span class="pun">-&gt;</span><span class="pln">link</span><span class="pun">;</span><span class="pln">
	</span><span class="kwd">last</span><span class="pun">-&gt;</span><span class="pln">link </span><span class="pun">=</span><span class="pln"> tmp</span><span class="pun">;</span><span class="pln">
	</span><span class="kwd">last</span><span class="pln"> </span><span class="pun">=</span><span class="pln"> tmp</span><span class="pun">;</span><span class="pln">
	</span><span class="kwd">return</span><span class="pln"> </span><span class="kwd">last</span><span class="pun">;</span><span class="pln">
</span><span class="pun">}</span><span class="com">/*End of addatend( )*/</span>

Output:

Enter the number of nodes : 3
Enter the element to be inserted : 55
Enter the element to be inserted : 43
Enter the element to be inserted : 24
Enter the number of nodes : 4
Enter the element to be inserted : 1
Enter the element to be inserted : 2
Enter the element to be inserted : 3
Enter the element to be inserted : 4
First list is :  55 43 24
Second list is :  1 2 3 4
Concatenated list is  : 55 43 24 1 2 3 4
Press any key to continue . . .

Explanation:

C Program to concatenate two circular linked lists

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