最短路径(Dijikstra和Floyed)

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>

typedef unsigned int ssize_t;

const ssize_t MAXSIZE = 20;

static ssize_t  graph  [MAXSIZE][MAXSIZE];
static ssize_t  node_num;
static char 	node   [MAXSIZE];


#define FLOYED

#ifdef DIJIKSTRA

static ssize_t 	dist   [MAXSIZE];
static char 	path   [MAXSIZE];
static bool 	visited[MAXSIZE];


void find_path_from(char node)
{
	ssize_t i = 0, j = 0;
	ssize_t start_index = node - 'A';
	ssize_t cur_min_path = 0;
	char cur_start_index = 0;
	
	visited[start_index] = true;
	
	for(i = 0; i < node_num - 1; i++)	
	{
		if(graph[start_index][i] < UINT_MAX)
			dist[i] = graph[start_index][i];
		else
			dist[i] = UINT_MAX;			
	}
	path[start_index] = 'A' + start_index;
	dist[start_index] = 0;

	for(j = 0; j < node_num; j++)
	{
		cur_min_path = UINT_MAX;
		for(i = 0; i < node_num; i++)
		{
			if((visited[i] == false)
				&& (dist[i] < cur_min_path))
			{
				cur_min_path = dist[i];
				cur_start_index = i;
			}		
		}
		visited[cur_start_index] = true;

		for(i = 0; i < node_num; i++)
		{
			if((visited[i] == false) &&
				(dist[i] > dist[cur_start_index] + graph[cur_start_index][i]))
			{
				dist[i] = dist[cur_start_index] + graph[cur_start_index][i];
				path[i] = cur_start_index + 'A';
			}
		}						
	}	
}

#endif

#ifdef FLOYED

void floyed()
{
	int k = 0, i = 0, j = 0;
	for(k = 0; k < node_num; k++)
	{
		for(i = 0; i < node_num; i++)
		{
			for(j = 0; j < node_num; j++)
			{
				if(graph[i][j] > graph[i][k] + graph[k][j])
					graph[i][j] = graph[i][k] + graph[k][j];
			}
		}		
	}
}

#endif

int 
main(ssize_t argc, char * argv [ ])
{
	ssize_t i = 0, j = 0;
	
	ssize_t edge_num = 0;
	ssize_t distance = 0;
	char start_node, end_node;

#ifdef DIJIKSTRA
	memset(graph, 0xFF, MAXSIZE * MAXSIZE * sizeof(ssize_t));
	memset(dist, 0xFF, MAXSIZE * sizeof(ssize_t));
#endif

	printf("请输入节点数量(小于%d):", MAXSIZE);
	scanf("%u", &node_num);

	for(i = 0; i < node_num; i++)	
		node[i] = 'A' + i;		

	printf("节点编号已自动分配为:%c-%c。\n", 'A', node[node_num - 1]);

	printf("请输入边的数量:");
	scanf("%u", &edge_num);

	while(getchar()!='\n');
	for(i = 0; i < edge_num; i++)
	{
		printf("请输入第%d条边(如'A-B:20'):", i + 1 );
		scanf("%c-%c:%u",&start_node, &end_node, &distance);
		graph[start_node - 'A'][end_node - 'A'] = distance;
		graph[end_node - 'A'  ][start_node - 'A'] = distance;		
		while(getchar()!='\n');
	}	

#ifdef DIJIKSTRA
	find_path_from('A');	

	for(i = 0; i < node_num; i++)
	{
		printf("%c->%c:%u\n", 'A', node[i], dist[i]);
	}
#endif

#ifdef FLOYED
	floyed();
	for(i = 0; i < node_num; i++)
	{
		printf("%c->%c:%u\n", 'A', node[i], graph[0][i]);
	}
#endif



	return 0;
}