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CloneGraph.cpp
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107 lines (97 loc) · 3.58 KB
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//============================================================================
// Clone an undirected graph. Each node in the graph contains a label and a
// list of its neighbors.
//
// Note:
// 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.
//
//============================================================================
#include <iostream>
#include <unordered_map>
#include <queue>
#include <vector>
using namespace std;
/**
* Definition for undirected graph.
*/
struct UndirectedGraphNode {
int label;
vector<UndirectedGraphNode *> neighbors;
UndirectedGraphNode(int x) : label(x) {};
};
class Solution {
public:
UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) {
return clone1(node);
}
// BFS
UndirectedGraphNode *clone1(UndirectedGraphNode *graph) {
if (!graph) return NULL;
unordered_map<UndirectedGraphNode*, UndirectedGraphNode*> table;
queue<UndirectedGraphNode *> queue;
queue.push(graph);
UndirectedGraphNode *res = new UndirectedGraphNode(graph->label);
table[graph] = res;
while (!queue.empty()) {
UndirectedGraphNode *curNode = queue.front();
queue.pop();
int n = curNode->neighbors.size();
for (int i = 0; i < n; i++) {
UndirectedGraphNode* neighbor = curNode->neighbors[i];
if (table.find(neighbor) == table.end()) {
// no copy exists
UndirectedGraphNode* newNode = new UndirectedGraphNode(neighbor->label);
(table[curNode]->neighbors).push_back(newNode);
table[neighbor] = newNode;
queue.push(neighbor);
} else {
// a copy already exists
UndirectedGraphNode* copy = table[neighbor];
(table[curNode]->neighbors).push_back(copy);
}
}
}
return res;
}
// DFS
UndirectedGraphNode *clone2(UndirectedGraphNode *graph) {
if (graph == NULL) return NULL;
UndirectedGraphNode *res = new UndirectedGraphNode(graph->label);
unordered_map<UndirectedGraphNode*, UndirectedGraphNode*> table;
table[graph] = res;
cloneHelper2(graph, table);
return res;
}
void cloneHelper2(UndirectedGraphNode *curNode, unordered_map<UndirectedGraphNode*, UndirectedGraphNode*> &table) {
for (size_t i = 0; i < curNode->neighbors.size(); i++) {
UndirectedGraphNode* neighbor = curNode->neighbors[i];
if (table.find(neighbor) == table.end()) {
// no copy exists
UndirectedGraphNode* newNode = new UndirectedGraphNode(neighbor->label);
(table[curNode]->neighbors).push_back(newNode);
table[neighbor] = newNode;
cloneHelper2(neighbor, table);
}
else {
// a copy already exists
UndirectedGraphNode* copy = table[neighbor];
(table[curNode]->neighbors).push_back(copy);
}
}
}
};
int main() {
return 0;
}