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/*
Author: Annie Kim, anniekim.pku@gmail.com
Date: Sep 26, 2013
Problem: Clone Graph
Difficulty: Easy
Source: http://oj.leetcode.com/problems/clone-graph/
Notes:
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 from 0 to N - 1, where N is the total nodes in the graph.
We use # as a separator for each node, and , as a separator for each neighbor of the node.
As an example, consider the serialized graph {1,2#2#2}.
The graph has a total of three nodes, and therefore contains three parts as separated by #.
Connect node 0 to both nodes 1 and 2.
Connect node 1 to node 2.
Connect node 2 to node 2 (itself), thus forming a self-cycle.
Visually, the graph looks like the following:
1
/ \
/ \
0 --- 2
/ \
\_/
Solution: 1. DFS. 2. BFS.
*/
/**
* Definition for undirected graph.
* struct UndirectedGraphNode {
* int label;
* vector<UndirectedGraphNode *> neighbors;
* UndirectedGraphNode(int x) : label(x) {};
* };
*/
class Solution {
public:
typedef UndirectedGraphNode GraphNode;
typedef unordered_map<GraphNode *, GraphNode *> MAP;
GraphNode *cloneGraph(GraphNode *node) {
return cloneGraph_1(node);
}
// DFS
GraphNode *cloneGraph_1(GraphNode *node) {
MAP map;
return cloneGraphRe(node, map);
}
GraphNode *cloneGraphRe(GraphNode *node, MAP &map) {
if (!node) return NULL;
if (map.find(node) != map.end())
return map[node];
GraphNode *newNode = new GraphNode(node->label);
map[node] = newNode;
for (int i = 0; i < node->neighbors.size(); ++i)
newNode->neighbors.push_back(cloneGraphRe(node->neighbors[i], map));
return newNode;
}
// BFS
GraphNode *cloneGraph_2(GraphNode *node) {
if (!node) return NULL;
queue<GraphNode*> q;
q.push(node);
MAP map;
map[node] = new GraphNode(node->label);
while (!q.empty())
{
GraphNode *oriNode = q.front(); q.pop();
GraphNode *newNode = map[oriNode];
for (int i = 0; i < oriNode->neighbors.size(); ++i)
{
GraphNode *oriNeighbor = oriNode->neighbors[i];
if (map.find(oriNeighbor) != map.end()) {
newNode->neighbors.push_back(map[oriNeighbor]);
continue;
}
GraphNode *newNeighbor = new GraphNode(oriNeighbor->label);
newNode->neighbors.push_back(newNeighbor);
map[oriNeighbor] = newNeighbor;
q.push(oriNeighbor);
}
}
return map[node];
}
};