B3647 【模板】Floyd

使用弗洛伊德-华沙算法：

#include <iostream>
using namespace std;
#define INF 0x3f3f3f3f

int adjm[101][101], dist[101][101];

int main() {
  int n, m;
  cin >> n >> m;
  for (int i = 1; i <= m; i++) {  
      int u, v, w;
      cin >> u >> v >> w;
      adjm[u][v] = adjm[u][v] ? min(adjm[u][v], w) : w;
      adjm[v][u] = adjm[v][u] ? min(adjm[v][u], w) : w;
  }

  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= n; j++) {
      if (i == j) {
        dist[i][j] = 0;
      } else if (adjm[i][j]) {
        dist[i][j] = adjm[i][j];
      } else {
        dist[i][j] = INF;
      }
    }
  }
  
  for (int k = 1; k <= n; k++) {
    for (int i = 1; i <= n; i++) {
      for (int j = 1; j <= n; j++) {
        dist[i][j] = min(dist[i][j],dist[i][k]+dist[k][j]);
      }
    }
  }
  
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= n; j++) {
      cout << dist[i][j] << ' ';
    }
    cout << endl;
  }
  return 0;
}

使用贝尔曼-福特算法：

#include <iostream>
#include <vector>
#include <tuple>
using namespace std;
#define INF 0x3f3f3f3f

vector<tuple<int,int,int>> edges;
int dist[10001];

int main() {
  int n, m;
  cin >> n >> m;
  for (int i = 1; i <= m; i++) {
    int u, v, w;
    cin >> u >> v >> w;
    edges.push_back({u,v,w});
    edges.push_back({v,u,w});
  }

  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= n; j++) {
      dist[j] = INF;
    }
    dist[i] = 0;
    for (int j = 1; j <= n-1; j++) {
      for (auto e : edges) {
        int u, v, w;
        tie(u, v, w) = e;
        dist[v] = min(dist[v], dist[u]+w);
      }
    }
    for (int j = 1; j <= n; j++) {
      cout << dist[j] << ' ';
    }
    cout << endl;
  }
}