C语言实现Floyd算法 C语言实现Floyd算法

#include <stdio.h> 
#include <stdlib.h> 
#include <limits.h> 
#define NUM 4 
 
typedef struct MGraph  /* 邻接表存储结构 */ 
{ 
  int edges[NUM][NUM]; 
  int n,e; 
} MGraph; 
 
MGraph *build_mgraph(); 
void Floyd(MGraph *mgraph); 
void Ppath(int path[][NUM], int i, int j); 
void Dispath(int A[][NUM], int path[][NUM], int n); 
 
int main(void) 
{ 
  MGraph *mgraph; 
 
  printf("\n*************************************************************\n"); 
  printf("该图的矩阵表示为:\n"); 
  mgraph=build_mgraph(); 
  printf("\n*************************************************************\n"); 
  printf("各顶点间最短路径为:\n"); 
  Floyd(mgraph); 
  printf("\n*************************************************************\n"); 
  
  return 0; 
} 
 
MGraph *build_mgraph() 
{ 
  int i,j; 
  int num_e=0; 
  MGraph *mgraph=(MGraph *)malloc(sizeof(MGraph)); 
  int matrix[NUM][NUM]={{0,5,INT_MAX,7}, 
    {INT_MAX,0,4,2}, 
    {3,3,0,2}, 
    {INT_MAX,INT_MAX,1,0}}; 
  for(i=0;i<NUM;i++) 
  { 
  for(j=0;j<NUM;j++) 
  { 
   mgraph->edges[i][j]=matrix[i][j]; 
   if(matrix[i][j]!=0 && matrix[i][j]!=INT_MAX) 
   num_e++; 
  } 
  } 
  mgraph->n=NUM; 
  mgraph->e=num_e; 
 
  printf("node=%d;edges=%d\n",mgraph->n,mgraph->e); 
  for(i=0;i<NUM;i++) 
  { 
  for(j=0;j<NUM;j++) 
  { 
   if(mgraph->edges[i][j]!=INT_MAX) 
   printf("%3d",mgraph->edges[i][j]); 
   else 
   printf("%3c",'&'); 
  } 
  printf("\n"); 
  } 
 
  return mgraph; 
} 
 
void Floyd(MGraph *mgraph) 
{ 
  int A[NUM][NUM],path[NUM][NUM]; 
  int i,j,k; 
 
  for(i=0;i<mgraph->n;i++) 
  { 
  for(j=0;j<mgraph->n;j++) 
  { 
   A[i][j]=mgraph->edges[i][j]; 
   path[i][j]=-1; 
  } 
  } 
 
  for(k=0;k<mgraph->n;k++) 
  { 
  for(i=0;i<mgraph->n;i++) 
  { 
   for(j=0;j<mgraph->n;j++) 
   { 
   if(A[i][k]!=INT_MAX && A[k][j]!=INT_MAX && A[i][j]>A[i][k]+A[k][j]) 
   { 
    A[i][j]=A[i][k]+A[k][j]; 
    path[i][j]=k; 
   } 
   } 
  } 
  } 
 
  Dispath(A,path,mgraph->n); 
} 
 
void Ppath(int path[][NUM], int i, int j) 
{ 
  int k; 
 
  k=path[i][j]; 
  if(k==-1) 
  return; 
  Ppath(path,i,k); 
  printf("%d,",k); 
  Ppath(path,k,j); 
} 
void Dispath(int A[][NUM], int path[][NUM], int n) 
{ 
  int i,j; 
  for(i=0;i<n;i++) 
  { 
  for(j=0;j<n;j++) 
  { 
   if(A[i][j]==INT_MAX) 
   printf("%d-%d have no path",i,j); 
   printf("%d-%d-%d: ",i,j,A[i][j]); 
   printf("%d,",i); 
   Ppath(path,i,j); 
   printf("%d\n",j); 
  } 
  } 
}