[LeetCode][JavaScript]Clone Graph

Clone Graph 

Clone an undirected graph. Each node in the graph contains a label and a list of its neighbors.

OJ's undirected graph serialization:

Nodes are labeled uniquely.

We use # as a separator for each node, and , as a separator for node label and each neighbor of the node.

As an example, consider the serialized graph {0,1,2#1,2#2,2}.

The graph has a total of three nodes, and therefore contains three parts as separated by #.

1. First node is labeled as 0. Connect node 0 to both nodes 1 and 2.
2. Second node is labeled as 1. Connect node 1 to node 2.
3. Third node is labeled as 2. Connect node 2 to node 2 (itself), thus forming a self-cycle.

Visually, the graph looks like the following:

       1
      / 
     /   
    0 --- 2
         / 
         \_/

https://leetcode.com/problems/clone-graph/

---

节点是唯一的，就是要注意像例子中这样从2到2的环，有个test case是{0,0,0}

DFS递归解法：

/**
 * Definition for undirected graph.
 * function UndirectedGraphNode(label) {
 *     this.label = label;
 *     this.neighbors = [];   // Array of UndirectedGraphNode
 * }
 */
/**
 * @param {UndirectedGraphNode} graph
 * @return {UndirectedGraphNode}
 */
var cloneGraph = function(graph) {
    var visited = {};
    if(graph === null){
        return null;
    }else{
        return dfs(graph);
    }

    function dfs(node){
        var newNode = null;
        if(visited[node.label]){
            newNode = visited[node.label];
        }else{
            newNode = new UndirectedGraphNode(node.label);
            visited[node.label] = newNode;
        }
        for(var i = 0; i < node.neighbors.length; i++){
            if(node.neighbors[i].label !== node.label){
                if(!visited[node.neighbors[i].label]){
                    newNode.neighbors.push(dfs(node.neighbors[i]));
                }else{
                    newNode.neighbors.push(visited[node.neighbors[i].label]);
                }
            }else{
                newNode.neighbors.push(visited[node.label]);
            }
        }
        return newNode; 
    }   
};

BFS非递归解法:

/**
 * Definition for undirected graph.
 * function UndirectedGraphNode(label) {
 *     this.label = label;
 *     this.neighbors = [];   // Array of UndirectedGraphNode
 * }
 */

/**
 * @param {UndirectedGraphNode} graph
 * @return {UndirectedGraphNode}
 */
var cloneGraph = function(graph) {
    var visited = {};
    var queue = [];
    if(graph === null){
        return null;
    }else{
        visited[graph.label] = new UndirectedGraphNode(graph.label);
        queue.push(graph);
        bfs();
        return visited[graph.label];
    }

    function bfs(){
        while(queue.length > 0){
            var node = queue.shift();
            var newNode = visited[node.label];
            for(var i = 0; i < node.neighbors.length; i++){
                if(node.neighbors[i].label !== node.label){
                    var neighbor = node.neighbors[i];
                    var newNeighbor = null;
                    if(!visited[neighbor.label]){
                        newNeighbor = new UndirectedGraphNode(neighbor.label);
                        visited[neighbor.label] = newNeighbor;
                        queue.push(neighbor);
                    }else{
                        newNeighbor = visited[neighbor.label];
                    }
                    newNode.neighbors.push(newNeighbor);
                }else{
                    newNode.neighbors.push(visited[node.label]);
                }
            }
        }
    } 
};