求图的任两结点间的最短距离，采用动态规划原理的Floyd算法，算法具体解释见另一篇原创 https://blog.csdn.net/gnosed/article/details/78956449 ，还提到求一个顶点到其他顶点的Dijkstra算法。下面是一个例子，只输出了最短路径的值。
#include <stdio.h>
#define Adjtype int
#define VN 10
#define MAX 99
struct GraphMatrix {
Adjtype arc[VN][VN];
} pgraph;
struct Shortpath {
Adjtype a[VN][VN];
int nextvex[VN][VN];
} ppath;
void print( )
{
for( int i = 0; i < VN; i++ ) {
for( int j = 0; j < VN; j++ ) {
printf("%d ",ppath.a[i][j]);
}
printf( "\n" );
}
}
void floyd( )
{
for( int i = 0; i < VN; i++ ) //initialize
for( int j = 0; j < VN; j++ ) {
ppath.a[i][j] = pgraph.arc[i][j];
if( pgraph.arc[i][j] != MAX )
ppath.nextvex[i][j] = j;
else
ppath.nextvex[i][j] = -1;
}
for( int k = 0; k < VN; k++ ) //iterate calculate *ppath
for( int i = 0; i < VN; i++ )
for( int j = 0; j < VN; j++ ) {
if( pgraph.arc[i][k] == MAX || pgraph.arc[k][j] == MAX )
continue;
if( ppath.a[i][j] > pgraph.arc[i][k] + pgraph.arc[k][j] ) { //revise *ppath
ppath.a[i][j] = pgraph.arc[i][k] + pgraph.arc[k][j];
ppath.nextvex[i][j] = ppath.nextvex[i][k];
}
}
}
int main()
{
for( int i = 0; i < VN; i++ )
for( int j = 0; j < VN; j++ )
scanf( "%d", &pgraph.arc[i][j] );
floyd();
print();
return 0;
}
输入样例
0 99 8 7 6 5 4 3 2 1
99 0 99 8 7 6 5 4 3 2
8 99 0 99 8 7 6 5 4 3
7 8 99 0 99 8 7 6 5 4
6 7 8 99 0 99 8 7 6 5
5 6 7 8 99 0 99 8 7 6
4 5 6 7 8 99 0 99 8 7
3 4 5 6 7 8 99 0 99 8
2 3 4 5 6 7 8 99 0 99
1 2 3 4 5 6 7 8 99 0输出样例
0 3 4 5 6 5 4 3 2 1
3 0 5 6 7 6 5 4 3 2
4 5 0 7 8 7 6 5 4 3
5 6 7 0 9 8 7 6 5 4
6 7 8 9 0 11 8 7 6 5
5 6 7 8 11 0 9 8 7 6
4 5 6 7 8 9 0 7 6 5
3 4 5 6 7 8 7 0 5 4
2 3 4 5 6 7 6 5 0 3
1 2 3 4 5 6 5 4 3 0