核心代码：

void dijkstra() {
  dis[1] = 0;
  lmi[1] = lma[1] = L[1];
  res = min(res, dis[1] + w[1]);

  for (int i = 0; i < n; ++i) {
    int t = -1;
    for (int j = 1; j <= n; ++j) {
      if (!st[j] && (t == -1 || dis[j] < dis[t])) {
	t = j;
      }
    }
    st[t] = 1;

    for (int j = 1; j <= n; ++j) {
      int mi = min(lmi[t], L[j]),
	ma = max(lma[t], L[j]), ga = abs(mi - ma);
      if (g[t][j] != INF && ga <= M) {
	dis[j] = min(dis[j], dis[t] + g[t][j]);
	lmi[j] = mi;
	lma[j] = ma;
	res = min(res, dis[j] + w[j]);
      }
    }
  }
}