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：

#include <iostream>
#include <cstring>

using namespace std;

#define MAX_POINT 1024
#define MAX_EDGE 16384

int N, M;
int d[MAX_POINT][MAX_POINT];

void floyd() {
  for (int k = 1; k <= N; k++) {
    for (int i = 1; i <= N; i++) {
      for (int j = 1; j <= N; j++) {
        if (k == i || i == j || j == k)
          continue;
        d[i][j] = min(d[i][j], d[i][k] + d[k][j]);
      }
    }
  }
}

int main() {
  memset(d, 1, sizeof(d));
  scanf("%d%d", &N, &M);
  for (int i = 1; i <= N; i++)
    d[i][i] = 0;
  for (int i = 0; i < M; i++) {
    int a, b, len;
    scanf("%d%d%d", &a, &b, &len);
    d[a][b] = d[b][a] = min(d[a][b], len);
  }

  floyd();

  for (int i = 1; i <= N; i++) {
    for (int j = 1; j < N; j++)
      printf("%d ", d[i][j]);
    printf("%d
", d[i][N]);
  }
  return 0;
}