TheAlgorithms-C/data_structures/graphs/euler.c

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#include <stdbool.h>
#include <stdio.h>
#include "Graph.h"
// Return the number of vertices that v is
// connected to
int degree(Graph g, int nV, Vertex v)
{
int deg = 0;
Vertex w;
for (w = 0; w < nV; w++)
if (adjacent(g, v, w))
deg++;
return deg;
}
// If start from vertex v, decide if the
// graph has euler path
bool hasEulerPath(Graph g, int nV, Vertex v, Vertex w)
{
if (v != w)
{
if (degree(g, nV, v) % 2 == 0 || degree(g, nV, w) % 2 == 0)
return false;
}
else if (degree(g, nV, v) % 2 != 0)
{
return false;
}
Vertex x;
for (x = 0; x < nV; x++)
if (x != v && x != w && degree(g, nV, x) % 2 != 0)
return false;
return true;
}
int main(void)
{
Edge e;
int n;
printf("Enter the number of vertices: ");
scanf("%d", &n);
Graph g = newGraph(n);
Vertex src, dest;
printf("Enter source node: ");
scanf("%d", &src);
printf("Enter destination node: ");
scanf("%d", &dest);
printf("Enter an edge (from): ");
while (scanf("%d", &e.v) == 1)
{
printf("Enter an edge (to): ");
scanf("%d", &e.w);
insertEdge(g, e);
printf("Enter an edge (from): ");
}
printf("Finished.\n");
printf("The graph has ");
if (hasEulerPath(g, n, src, dest))
printf("an");
else
printf("no");
printf(" Euler path from %d to %d.\n", src, dest);
freeGraph(g);
return 0;
}
// By
// .----------------. .----------------. .----------------.
// .-----------------. .----------------. .----------------.
// | .--------------. || .--------------. || .--------------. ||
// .--------------. | | .--------------. || .--------------. | | | _________ |
// || | _____ _____ | || | __ | || | ____ _____ | | | | ____ ____
// | || | ____ | | | | | _ _ | | || ||_ _||_ _|| || | / \
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// \_| | || | | | | | | || | / /\ \ | || | | \ | | | | | | |
// |__| | | || | / .--. \ | | | | | | | || | | ' ' | | || |
// / ____ \ | || | | |\ \| | | | | | | __ | | || | | | | | | |
// | | _| |_ | || | \ `--' / | || | _/ / \ \_ | || | _| |_\ |_
// | | | | _| | | |_ | || | \ `--' / | | | | |_____| | || | `.__.'
// | || ||____| |____|| || ||_____|\____| | | | | |____||____| | || | `.____.'
// | | | | | || | | || | | || | | | | |
// | || | | | | '--------------' || '--------------' ||
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// |
// '----------------' '----------------' '----------------'
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// Email : z5261243@unsw.edu.au
// hhoanhtuann@gmail.com