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[Leetcode]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 #
.
- First node is labeled as
0
. Connect node0
to both nodes1
and2
. - Second node is labeled as
1
. Connect node1
to node2
. - Third node is labeled as
2
. Connect node2
to node2
(itself), thus forming a self-cycle.
Visually, the graph looks like the following:
1 / / 0 --- 2 / \_/
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Depth-first Search Breadth-first Search Graph题目要求复制一个图
根据题意我们发现lable是独一无二的,它标志了一个node。因此我们可以用关联容器map,用lable作为KEY来保存已经创建过的点的地址
先写了一个递归的版本:
class Solution {public:<span style="white-space:pre"> </span>UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) {<span style="white-space:pre"> </span>if (NULL == node) return NULL;<span style="white-space:pre"> </span>map<int, UndirectedGraphNode *> occured;<span style="white-space:pre"> </span>return clone(node, occured);<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>UndirectedGraphNode *clone(UndirectedGraphNode *node, map<int, UndirectedGraphNode *> &occured){<span style="white-space:pre"> </span>if (occured.count(node->label) == 0){<span style="white-space:pre"> </span>UndirectedGraphNode *newNode = new UndirectedGraphNode(node->label);<span style="white-space:pre"> </span>occured[node->label] = newNode;<span style="white-space:pre"> </span>for (int i = 0; i < node->neighbors.size(); i++){<span style="white-space:pre"> </span>newNode->neighbors.push_back(clone(node->neighbors[i], occured));<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>return newNode;<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>else{<span style="white-space:pre"> </span>return occured[node->label];<span style="white-space:pre"> </span>}<span style="white-space:pre"> </span>}};
然后又写了一个非递归版本,这一次采用每个节点在原图中的地址作为KEY,来储存对应新节点的地址
用一个queue来保存要访问的节点
class Solution { public: UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) { if (NULL == node) return NULL; map<UndirectedGraphNode *, UndirectedGraphNode *> occured; queue<UndirectedGraphNode *> visit; visit.push(node); while (!visit.empty()){ UndirectedGraphNode *cur = visit.front(); visit.pop(); if (occured.count(cur) == 0){ UndirectedGraphNode *newNode = new UndirectedGraphNode(cur->label); occured[cur] = newNode; } for (int i = 0; i < cur->neighbors.size(); i++){ UndirectedGraphNode *tmp = cur->neighbors[i]; if (occured.count(tmp) == 0){ UndirectedGraphNode *newNode = new UndirectedGraphNode(tmp->label); occured[tmp] = newNode; visit.push(tmp); } occured[cur]->neighbors.push_back(occured[tmp]); } } return occured[node]; } };
两段代码都是一遍AC
[Leetcode]Clone Graph
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