hihoCoder#1089 最短路径·二：Floyd算法

原题地址

 

感觉Floyd算法比Dijkstra还要简单。。

唯一需要注意的是，初始的距离默认值不要设过大，否则溢出就不好了，根据题意，只要大于10^3即可

 

代码：

 1 #include <iostream>

 2 #include <cstring>

 3 

 4 using namespace std;

 5 

 6 #define MAX_POINT 1024

 7 #define MAX_EDGE 16384

 8 

 9 int N, M;

10 int d[MAX_POINT][MAX_POINT];

11 

12 void floyd() {

13   for (int k = 1; k <= N; k++) {

14     for (int i = 1; i <= N; i++) {

15       for (int j = 1; j <= N; j++) {

16         if (k == i || i == j || j == k)

17           continue;

18         d[i][j] = min(d[i][j], d[i][k] + d[k][j]);

19       }

20     }

21   }

22 }

23 

24 int main() {

25   memset(d, 1, sizeof(d));

26   scanf("%d%d", &N, &M);

27   for (int i = 1; i <= N; i++)

28     d[i][i] = 0;

29   for (int i = 0; i < M; i++) {

30     int a, b, len;

31     scanf("%d%d%d", &a, &b, &len);

32     d[a][b] = d[b][a] = min(d[a][b], len);

33   }

34 

35   floyd();

36 

37   for (int i = 1; i <= N; i++) {

38     for (int j = 1; j < N; j++)

39       printf("%d ", d[i][j]);

40     printf("%d\n", d[i][N]);

41   }

42   return 0;

43 }