Uniform Cost Priority Expansion

function uniformCostSearch(graph, start, goal) {
  const frontier = [{ node: start, cost: 0 }];
  const visited = new Set();
  while (frontier.length > 0) {
    frontier.sort((a, b) => b.cost - a.cost);
    const { node, cost } = frontier.shift();
    if (node === goal) return cost;
    visited.add(node);
    for (const [next, w] of graph[node]) {
      if (!visited.has(next)) frontier.push({ node: next, cost: cost + w });
    }
  }
  return -1;
}