最短路径（Floyd_Warshall算法）

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

#define SIZE 8
#define INFINATE 99999
#define IN_FILE "distance.txt"

int matrix[SIZE][SIZE];
int next[SIZE][SIZE]={0};

/**
 * find the shortest path between i and j
 */
void getPath(int i,int j)
{
	if(INFINATE==matrix[i][j])
	{
		printf("no path");
	}

	int intermediate=next[i][j];
	if(0==intermediate)
	{
		printf(" ");
	}
	else
	{
		getPath(i,intermediate);
		printf("%d\t",intermediate);
		getPath(intermediate,j);
	}
	printf("\n");
}
/**
 * display the final matrix
 */
void printMatrix()
{
	int i,j;
	for(i=0;i<SIZE;i++)
	{
		for(j=0;j<SIZE;j++)
		{
			printf("%d\t",matrix[i][j]);
		}
		printf("\n");
	}
}

void readin()
{
	FILE *fpin=fopen(IN_FILE,"r");

	if(NULL==fpin)
	{
		fprintf(stderr,"cannot open file:%s\n",IN_FILE);
		exit(0);
	}

	int i,j;

	//read the original matrix into the mem
	for(i=0;i<SIZE;i++){
		for(j=0;j<SIZE;j++){
			fscanf(fpin,"%d\n",&matrix[i][j]);
		}
	}
}

int main()
{
	readin();
	printf("original matrix:\n");
	printMatrix();
	printf("\n");
	int k,i,j,sum;
	for(k=0;k<SIZE;k++)
	{
		for(i=0;i<SIZE;i++)
		{
			for(j=0;j<SIZE;j++)
			{
				//core center for matrix update
				if(INFINATE!=matrix[i][k] && INFINATE!=matrix[k][j])
					sum=matrix[i][k]+matrix[k][j];
				else 
					sum=INFINATE;

				if(matrix[i][j]>sum)
				{
					//update the value
					matrix[i][j]=sum;

					//record the path
					next[i][j]=k;
				}
			}
		}
	}

	printMatrix();

	getPath(1,1);
}