133. Clone Graph

刷
July-03-2019

这个题比较诡异。题里说的unique是指任何VAL是1的点其实都是指向1个。
做法是先走一遍，记录所有的已经存在的node： Node[100]。
复制一遍记录的所有Node，此时复制的只有里面的val，复制出的copyNode的neighbor还没做好，也就是说复制出来的copyNodes之间的指向关系还没建立好。
然后走一遍复制过的所有copyNodes,通过copyNode.val来找到对应的node，然后把node里的所有neighbor加到copyNode的neighbor里：比如neighbor-3要加在copyNode里的是copy[3]
有点绕= =

class Solution {
    public Node cloneGraph(Node node) {
        if (node == null) return null;
        Node[] nodes = fillNodes(node);
        Node[] copies = new Node[101];
        for (int i = 0; i < 101; i ++) {
            if (nodes[i] != null) {
                copies[i] = new Node(nodes[i].val, new ArrayList<>());
            }
        }

        Arrays.stream(copies).forEach(copy -> {
            if (copy != null) {
                nodes[copy.val].neighbors.stream().forEach(realNeighbor -> {
                    copy.neighbors.add(copies[realNeighbor.val]);
                });
            }
        });
        
        return copies[node.val];
        
    }
    
    public Node[] fillNodes(Node node) {
        Node[] nodes = new Node[101];
        boolean[] visited = new boolean[101];
        if (node == null) return nodes;
        ArrayDeque<Node> q = new ArrayDeque<>();
        q.offerLast(node);
        visited[node.val] = true;
        
        while (!q.isEmpty()) {
            Node tempNode = q.pollFirst();
            nodes[tempNode.val] = tempNode;
            tempNode.neighbors.stream()
                .filter(neighbor -> !visited[neighbor.val])
                .forEach(neighbor -> {
                    q.offerLast(neighbor);
                    visited[neighbor.val] = true;
                });
        }
        
        return nodes;
    }
}

---

四刷。。

这傻屌题都四刷了么。。

public class Solution {
    Map<Integer, UndirectedGraphNode> map = new HashMap<>();
    public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) {
        if (node == null) return null;
    
        if (!map.containsKey(node.label)) {
            map.put(node.label, new UndirectedGraphNode(node.label));
        } 
        UndirectedGraphNode res = map.get(node.label);
        res.neighbors = new ArrayList<UndirectedGraphNode>();
        
        for (UndirectedGraphNode n : node.neighbors) {
            if (!map.containsKey(n.label)) {
                res.neighbors.add(cloneGraph(n));
            } else {
                res.neighbors.add(map.get(n.label));
            }
        }
        
        return res;
    }
}