Skip to content

Commit 94882ec

Browse files
aish2002aish2002
authored
Added adjacency list in C++ (#3672)
1 parent cb38815 commit 94882ec

File tree

2 files changed

+226
-0
lines changed

2 files changed

+226
-0
lines changed

‎C-Plus-Plus/README.md

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -119,6 +119,7 @@
119119

120120
## Graphs
121121

122+
- [Adjacency List Representation](graphs/Adjacency_List.cpp)
122123
- [Articulation points in an Undirected Graph](graphs/Articulation_points.cpp)
123124
- [Bellman Ford's Algorithm](graphs/BellmanFord.cpp)
124125
- [Breadth First Search Tree Traversal](graphs/bfs.cpp)

‎C-Plus-Plus/graphs/Adjacency_List.cpp

Lines changed: 225 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,225 @@
1+
/* ADJACENCY LIST FOR REPRESENTING DIRECTED GRAPH
2+
It is a method of representing a digraph using 2 linked lists
3+
1. Node list
4+
2. Edge list corresponding to each node
5+
Edges arising from a node are stored in edge list of each node
6+
*/
7+
8+
#include <bits/stdc++.h>
9+
using namespace std;
10+
11+
/* Declare a structure for representing digraph with data and 2 links
12+
* link represents the edge between the parent node and next node (edge list)
13+
* pnext point to the next node from which new edges arise(node list)
14+
* g points to the graph
15+
*/
16+
typedef struct AdjacencyList
17+
{
18+
int data;
19+
struct AdjacencyList *link, *pnext;
20+
} AdjacencyList;
21+
AdjacencyList *g;
22+
23+
//to insert into the graph
24+
void insert_to_graph(AdjacencyList *g, int parent, int value)
25+
{
26+
//ptr points to the first node in the graph
27+
AdjacencyList *ptr = g->link, *p;
28+
//Check if the graph is empty
29+
if (g->link == NULL)
30+
{
31+
// ptr stores the value of parent node
32+
ptr = new AdjacencyList;
33+
ptr->data = parent;
34+
ptr->pnext = NULL;
35+
ptr->link = NULL;
36+
g->link = ptr;
37+
}
38+
else
39+
{
40+
//Search for parent in the node list
41+
while (ptr != NULL && ptr->data != parent)
42+
{
43+
p = ptr;
44+
ptr = ptr->pnext;
45+
}
46+
//If parent is not found in the node list insert as last node
47+
if (ptr == NULL)
48+
{
49+
ptr = new AdjacencyList;
50+
ptr->data = parent;
51+
ptr->pnext = NULL;
52+
ptr->link = NULL;
53+
p->pnext = ptr;
54+
}
55+
}
56+
//insert value in the edge list of parent node
57+
AdjacencyList *node;
58+
node = new AdjacencyList;
59+
node->data = value;
60+
node->link = NULL;
61+
node->pnext = NULL;
62+
//Traverse till the end of the edge list
63+
while (ptr->link != NULL)
64+
ptr = ptr->link;
65+
//Insert value as the last node in the edge list
66+
ptr->link = node;
67+
}
68+
69+
//To delete a node from the graph
70+
void delete_from_graph(AdjacencyList *g, int value)
71+
{
72+
//Set flag as 0 assuming value is not present in the graph
73+
int flag = 0;
74+
//If the graph is not empty
75+
if (g->link != NULL)
76+
{
77+
//ptr points to first node
78+
AdjacencyList *ptr = g->link, *p, *pre;
79+
//If the first node in the node list is value
80+
if (ptr->data == value)
81+
{
82+
g->link = ptr->pnext;
83+
flag = 1;
84+
}
85+
else
86+
{
87+
//Traverse the node list till value is found
88+
while (ptr->pnext != NULL && ptr->data != value)
89+
{
90+
p = ptr;
91+
ptr = ptr->pnext;
92+
}
93+
//If value is found delete node and entire edge list of the node
94+
if (ptr->data == value)
95+
{
96+
p->pnext = ptr->pnext;
97+
flag = 1;
98+
}
99+
}
100+
ptr = g->link;
101+
//Traverse till the end of the node list
102+
while (ptr != NULL)
103+
{
104+
p = ptr;
105+
//traverse the edge list of p till value is found
106+
while (p->link && p->data != value)
107+
{
108+
pre = p;
109+
p = p->link;
110+
}
111+
// If value is found in the edge list of p delete edge
112+
if (p->data == value)
113+
{
114+
pre->link = p->link;
115+
flag = 1;
116+
}
117+
ptr = ptr->pnext;
118+
}
119+
}
120+
//If flag is 0 value in not present in the graph
121+
if (flag == 0)
122+
printf("Node %d does not exist !\n", value);
123+
}
124+
125+
//to print the graph
126+
void print_graph(AdjacencyList *g)
127+
{
128+
//Check if graph is empty
129+
if (g->link == NULL)
130+
printf("Graph Empty !\n");
131+
else
132+
{
133+
AdjacencyList *ptr = g->link, *p;
134+
//Traverse the node list
135+
while (ptr)
136+
{
137+
p = ptr;
138+
printf("%d ->", ptr->data);
139+
//traverse the edge list of p and print all the nodes
140+
while (p->link)
141+
{
142+
printf(" %d", p->link->data);
143+
p = p->link;
144+
}
145+
printf("\n");
146+
ptr = ptr->pnext;
147+
}
148+
}
149+
}
150+
151+
int main()
152+
{
153+
AdjacencyList *g = (AdjacencyList *)malloc(sizeof(AdjacencyList) * 10);
154+
g->link = NULL;
155+
//menu driven program to insert, delete and print graph according to choice
156+
printf("1. Insert into graph\n2. Delete from graph\n3. Display\n4. Exit\n\n");
157+
while (1)
158+
{
159+
int choice;
160+
printf("Enter choice: ");
161+
scanf("%d", &choice);
162+
switch (choice)
163+
{
164+
case 1:
165+
{
166+
int parent, value;
167+
printf("Enter parent and value: ");
168+
scanf("%d %d", &parent, &value);
169+
insert_to_graph(g, parent, value);
170+
}
171+
break;
172+
173+
case 2:
174+
{
175+
int value;
176+
printf("Enter value: ");
177+
scanf("%d", &value);
178+
delete_from_graph(g, value);
179+
}
180+
break;
181+
182+
case 3:
183+
{
184+
print_graph(g);
185+
}
186+
break;
187+
188+
case 4:
189+
{
190+
return 0;
191+
}
192+
}
193+
}
194+
195+
return 0;
196+
}
197+
/*
198+
Sample I/O:
199+
1. Insert into graph
200+
2. Delete from graph
201+
3. Display
202+
4. Exit
203+
204+
Enter choice: 1
205+
Enter parent and value: 2 3
206+
Enter choice: 1
207+
Enter parent and value: 3 4
208+
Enter choice: 1
209+
Enter parent and value: 1 5
210+
Enter choice: 1
211+
Enter parent and value: 2 4
212+
Enter choice: 3
213+
2 -> 3 4
214+
3 -> 4
215+
1 -> 5
216+
Enter choice: 4
217+
*/
218+
/*
219+
TIME COMPLEXITY
220+
Insertion - O(n)
221+
Deletion - O(n^2)
222+
Print graph - O(n^2)
223+
Total time complexity of the program - O(n^2)
224+
SPACE COMPLEXITY- O(n)
225+
*/

0 commit comments

Comments
 (0)