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| class Graph {
private static class Edge {
private final int from;
private final int to;
private final int cost;
public Edge(int from, int to, int cost) {
this.from = from;
this.to = to;
this.cost = cost;
}
}
private final List<List<Edge>> nodeToEdgeListMap;
public Graph(int n, int[][] edges) {
nodeToEdgeListMap = new ArrayList<>(n);
for (int i = 0; i < n; i++) {
nodeToEdgeListMap.add(new ArrayList<>());
}
for (int[] edge : edges) {
Edge e = new Edge(edge[0], edge[1], edge[2]);
nodeToEdgeListMap.get(e.from).add(e);
}
}
public void addEdge(int[] edge) {
Edge e = new Edge(edge[0], edge[1], edge[2]);
nodeToEdgeListMap.get(e.from).add(e);
}
public int shortestPath(int node1, int node2) {
int[] nodeCostMap = new int[nodeToEdgeListMap.size()];
Arrays.fill(nodeCostMap, Integer.MAX_VALUE);
nodeCostMap[node1] = 0;
Queue<int[]> queue = new PriorityQueue<>(Comparator.comparingInt(o -> o[1]));
queue.offer(new int[]{node1, 0});
while (!queue.isEmpty()) {
int[] pair = queue.poll();
int node = pair[0], cost = pair[1];
if (node == node2) {
return cost;
}
for (Edge edge : nodeToEdgeListMap.get(node)) {
if (cost + edge.cost < nodeCostMap[edge.to]) {
nodeCostMap[edge.to] = cost + edge.cost;
queue.offer(new int[]{edge.to, nodeCostMap[edge.to]});
}
}
}
return -1;
}
}
|
References
2642. Design Graph With Shortest Path Calculator