TheAlgorithms-C/data_structures/graphs/hamiltonian.c

#include <stdbool.h>
#include <stdio.h>
#include "Graph.h"

#define MAX_NODES 1000

bool visited[MAX_NODES];

bool hamiltonR(Graph g, int nV, Vertex v, Vertex dest, int d)
{
    // v = current vertex considered
    // dest = destination vertex
    // d = distance "remaining" until path found

    Vertex w;
    if (v == dest)
    {
        return (d == 0);
    }
    else
    {
        visited[v] = true;
        for (w = 0; w < nV; w++)
        {
            if (adjacent(g, v, w) && !visited[w])
            {
                if (hamiltonR(g, nV, w, dest, d - 1))
                {
                    return true;
                }
            }
        }
    }
    visited[v] = false;
    return false;
}

bool hasHamiltonianPath(Graph g, int nV, Vertex src, Vertex dest)
{
    Vertex v;
    for (v = 0; v < nV; v++) visited[v] = false;
    return hamiltonR(g, nV, src, dest, nV - 1);
}

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 (hasHamiltonianPath(g, n, src, dest))
        printf("a");
    else
        printf("no");
    printf(" Hamiltonian 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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// / ____ \   | || |  | |\ \| |   | | | |   |  __  |   | || |  | |    | |  | |
// | |    _| |_     | || |   \ `--' /   | || | _/ /    \ \_ | || | _| |_\   |_
// | | | |  _| |  | |_  | || |  \  `--'  /  | | | |   |_____|    | || | `.__.'
// | || ||____|  |____|| || ||_____|\____| | | | | |____||____| | || | `.____.'
// | | | |              | || |              | || |              | || | | | | |
// | || |              | | | '--------------' || '--------------' ||
// '--------------' || '--------------' | | '--------------' || '--------------'
// |
//  '----------------'  '----------------'  '----------------'
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//  Email :    z5261243@unsw.edu.au
//             hhoanhtuann@gmail.com