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Graph.c
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Graph.c
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// Interface for a directed weighted graph ADT, where each vertex is
// identified by a number between 0 and N - 1, where N is the number of
// vertices.
// COMP2521 Assignment 2
// !!! DO NOT MODIFY THIS FILE !!!
#include <assert.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include "Graph.h"
struct GraphRep{
int nV;
AdjList *outLinks;
AdjList *inLinks;
};
static bool validVertex(Graph g, Vertex v);
static AdjList newAdjNode(Vertex v, int weight);
static AdjList adjListInsert(AdjList l, Vertex v, int weight);
static AdjList adjListDelete(AdjList l, Vertex v);
static bool inAdjList(AdjList l, Vertex v);
static void freeAdjList(AdjList l);
static void showAdjList(AdjList l);
////////////////////////////////////////////////////////////////////////
// Constructor/Destructor
Graph GraphNew(int nVertices) {
assert(nVertices > 0);
Graph g = malloc(sizeof(*g));
if (g == NULL) {
fprintf(stderr, "Couldn't allocate Graph!\n");
exit(EXIT_FAILURE);
}
g->nV = nVertices;
g->outLinks = calloc(nVertices, sizeof(AdjList));
g->inLinks = calloc(nVertices, sizeof(AdjList));
if (g->outLinks == NULL || g->inLinks == NULL) {
fprintf(stderr, "Couldn't allocate Graph!\n");
exit(EXIT_FAILURE);
}
return g;
}
void GraphFree(Graph g) {
assert(g != NULL);
for (Vertex i = 0; i < g->nV; i++) {
freeAdjList(g->outLinks[i]);
freeAdjList(g->inLinks[i]);
}
free(g->outLinks);
free(g->inLinks);
free(g);
}
////////////////////////////////////////////////////////////////////////
// Basic Graph Operations
void GraphInsertEdge(Graph g, Vertex src, Vertex dest, int weight) {
assert(g != NULL);
assert(validVertex(g, src));
assert(validVertex(g, dest));
assert(weight > 0);
g->outLinks[src] = adjListInsert(g->outLinks[src], dest, weight);
g->inLinks[dest] = adjListInsert(g->inLinks[dest], src, weight);
}
void GraphRemoveEdge(Graph g, Vertex src, Vertex dest) {
assert(g != NULL);
assert(validVertex(g, src));
assert(validVertex(g, dest));
g->outLinks[src] = adjListDelete(g->outLinks[src], dest);
g->inLinks[dest] = adjListDelete(g->inLinks[dest], src);
}
bool GraphIsAdjacent(Graph g, Vertex src, Vertex dest) {
assert(g != NULL);
assert(validVertex(g, src));
assert(validVertex(g, dest));
return inAdjList(g->outLinks[src], dest);
}
int GraphNumVertices(Graph g) {
assert(g != NULL);
return g->nV;
}
AdjList GraphOutIncident(Graph g, Vertex v) {
assert(g != NULL);
assert(validVertex(g, v));
return g->outLinks[v];
}
AdjList GraphInIncident(Graph g, Vertex v) {
assert(g != NULL);
assert(validVertex(g, v));
return g->inLinks[v];
}
////////////////////////////////////////////////////////////////////////
// Debugging
void GraphShow(Graph g) {
printf("#vertices = %d\n", g->nV);
printf("Vertices:\n");
for (Vertex i = 0; i < g->nV; i++) {
printf(" Vertex %2d\n", i);
printf(" Outlinks: ");
showAdjList(g->outLinks[i]);
printf(" In-links: ");
showAdjList(g->inLinks[i]);
printf("\n");
}
}
////////////////////////////////////////////////////////////////////////
// Helper Functions
/**
* Check if a given vertex is valid for a graph
*/
static bool validVertex(Graph g, Vertex v) {
return (v >= 0 && v < g->nV);
}
/**
* Creates a new AdjList node with the given vertex and weight.
*/
static AdjList newAdjNode(Vertex v, int weight) {
AdjList newNode = malloc(sizeof(*newNode));
if (newNode == NULL) {
fprintf(stderr, "Couldn't allocate new node!\n");
exit(EXIT_FAILURE);
}
newNode->v = v;
newNode->weight = weight;
newNode->next = NULL;
return newNode;
}
/*
* Inserts an AdjList node with the given vertex and weight into the
* given adjacency list, if the vertex is not already in the list.
* Ensures the adjacency list remains ordered by vertex number.
*/
static AdjList adjListInsert(AdjList l, Vertex v, int weight) {
if (l == NULL || v < l->v) {
AdjList n = newAdjNode(v, weight);
n->next = l;
return n;
} else if (v > l->v) {
l->next = adjListInsert(l->next, v, weight);
return l;
} else {
return l;
}
}
/*
* Deletes the AdjNode node with the given vertex from the given
* adjacency list, if it exists. Ensures the adjacency list remains
* ordered by vertex number.
*/
static AdjList adjListDelete(AdjList l, Vertex v) {
if (l == NULL || v < l->v) {
return l;
} else if (v == l->v) {
AdjList temp = l->next;
free(l);
return temp;
} else {
l->next = adjListDelete(l->next, v);
return l;
}
}
/**
* Checks if a vertex is in the given adjacency list, returning true or
* false as appropriate
*/
static bool inAdjList(AdjList l, Vertex v) {
if (l == NULL || v < l->v) {
return false;
} else if (v == l->v) {
return true;
} else {
return inAdjList(l->next, v);
}
}
/**
* Frees all of the memory associated with the given adjacency list.
*/
static void freeAdjList(AdjList l) {
if (l != NULL) {
freeAdjList(l->next);
free(l);
}
}
/**
* Outputs the given adjacency list to stdout.
*/
static void showAdjList(AdjList l) {
while (l != NULL) {
printf("(v: %2d, weight: %2d) -> ", l->v, l->weight);
l = l->next;
}
printf("X\n");
}