137 lines
3.6 KiB
C++
137 lines
3.6 KiB
C++
/*This is a C++ Program to check whether graph is DAG. In mathematics and computer science, a directed acyclic graph (DAG Listeni/’dæg/), is a directed graph with no directed cycles. That is, it is formed by a collection of vertices and directed edges, each edge connecting one vertex to another, such that there is no way to start at some vertex v and follow a sequence of edges that eventually loops back to v again.*/
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#include<stdio.h>
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#include<iostream>
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#include<conio.h>
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using namespace std;
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int c = 0;
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struct adj_list
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{
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int dest;
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adj_list *next;
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}*np = NULL, *np1 = NULL, *p = NULL, *q = NULL;
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struct Graph
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{
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int v;
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adj_list *ptr;
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} array[6];
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void addReverseEdge(int src, int dest)
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{
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np1 = new adj_list;
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np1->dest = src;
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np1->next = NULL;
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if (array[dest].ptr == NULL)
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{
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array[dest].ptr = np1;
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q = array[dest].ptr;
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q->next = NULL;
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}
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else
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{
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q = array[dest].ptr;
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while (q->next != NULL)
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{
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q = q->next;
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}
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q->next = np1;
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}
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}
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void addEdge(int src, int dest)
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{
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np = new adj_list;
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np->dest = dest;
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np->next = NULL;
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if (array[src].ptr == NULL)
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{
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array[src].ptr = np;
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p = array[src].ptr;
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p->next = NULL;
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}
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else
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{
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p = array[src].ptr;
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while (p->next != NULL)
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{
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p = p->next;
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}
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p->next = np;
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}
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//addReverseEdge(src, dest);
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}
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void print_graph(int n)
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{
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for (int i = 0; i < n; i++)
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{
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cout << "Adjacency List of " << array[i].v << ": ";
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while (array[i].ptr != NULL)
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{
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cout << (array[i].ptr)->dest << " ";
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array[i].ptr = (array[i].ptr)->next;
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}
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cout << endl;
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}
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}
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int checkDAG(int n)
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{
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int count = 0;
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int size = n - 1;
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for (int i = 0; i < n; i++)
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{
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//cout << "Adjacency List of " << array[i].v << ": ";
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if (count == size)
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{
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return 1;
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}
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if (array[i].ptr == NULL)
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{
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count++;
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for (int j = 0; j < n; j++)
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{
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while (array[j].ptr != NULL)
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{
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if ((array[j].ptr)->dest == (array[i].ptr)->dest)
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{
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(array[j].ptr)->dest = -1;
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}
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array[i].ptr = (array[i].ptr)->next;
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}
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}
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}
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}
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return 0;
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}
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int main()
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{
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int n = 6;
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cout << "Number of vertices: " << n << endl;
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for (int i = 0; i < n; i++)
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{
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array[i].v = i;
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array[i].ptr = NULL;
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}
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addEdge(0, 1);
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addEdge(1, 2);
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addEdge(1, 3);
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addEdge(3, 4);
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addEdge(4, 5);
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addEdge(5, 3);
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addEdge(5, 2);
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print_graph(n);
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cout << "The given graph is 'Directed Acyclic Graph' :";
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if (checkDAG(n) == 1)
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cout << " True";
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else
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cout << " False";
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}
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/*
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Number of vertices: 6
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Adjacency List of 0: 1
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Adjacency List of 1: 2 3
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Adjacency List of 2:
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Adjacency List of 3: 4
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Adjacency List of 4: 5
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Adjacency List of 5: 3 2
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The given graph is 'Directed Acyclic Graph' : True
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