hihoCoder#1081 最短路径·一

原题地址

Dijkstra算法，甚至都不用优化（堆或优先队列）即可过

代码：

#include <iostream>
#include <vector>
#include <set>
#include <cstring>

using namespace std;

#define MAX_POINT 1024
#define MAX_EDGE 16384

int N, M, S, T;
int graph[MAX_POINT][MAX_POINT];
int v[MAX_POINT];

void bfs() {
  v[S] = 1;
  while (true) {
    int k = 0;
    for (int i = 1; i <= N; i++) {
      if (!v[i] && graph[S][i] < graph[S][k])
        k = i;
    }
    if (k == T)
      break;
    v[k] = 1;
    for (int i = 1; i <= N; i++)
      if (!v[i] && graph[S][i] > graph[S][k] + graph[k][i])
        graph[S][i] = graph[S][k] + graph[k][i];
  }
}

int main() {
  memset(v, 0, sizeof(v));
  memset(graph, 64, sizeof(graph));

  scanf("%d%d%d%d", &N, &M, &S, &T);
  for (int i = 0; i < M; i++) {
    int u, v, len;
    scanf("%d%d%d", &u, &v, &len);
    graph[u][v] = graph[v][u] = min(graph[u][v], len);
  }

  bfs();

  printf("%d
", graph[S][T]);
}