133. Clone Graph

最新推荐文章于 2020-08-12 10:22:05 发布

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本文介绍了一种使用map记录已复制节点的无向图复制算法，避免了重复复制的问题，适用于节点唯一标记的图结构。

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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 #.

First node is labeled as 0. Connect node 0 to both nodes 1 and 2.
Second node is labeled as 1. Connect node 1 to node 2.
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:

题意：实现结构体的复制。

思路：借助map对复制过的元素做记录，以免重复复制。

/**
 * Definition for undirected graph.
 * struct UndirectedGraphNode {
 *     int label;
 *     vector<UndirectedGraphNode *> neighbors;
 *     UndirectedGraphNode(int x) : label(x) {};
 * };
 */
class Solution {
public:
	UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) {
		if (node == NULL)
			return NULL;
		auto iter = copies.find(node);
		if (iter != copies.end()){
			return iter->second;
		}

		UndirectedGraphNode *copy = new UndirectedGraphNode(node->label);
        copies[node] = copy;
		for (auto neigh : node->neighbors){
			copy->neighbors.push_back(cloneGraph(neigh));
		}
		
		return copy;
	}
private:
	map<UndirectedGraphNode*, UndirectedGraphNode*> copies;
};