使用DFS检查无向图连通性的C++程序
要检查图的连通性,我们将尝试使用任何遍历算法遍历所有节点。遍历完成后,如果存在任何未访问的节点,则该图未连接。

对于无向图,我们将选择一个节点并从中进行遍历。
在本例中,遍历算法是递归深度优先搜索 (DFS) 遍历。
输入 − 图的邻接矩阵
| 0 | 1 | 1 | 0 | 0 |
| 1 | 0 | 1 | 1 | 0 |
| 1 | 1 | 0 | 1 | 1 |
| 0 | 1 | 1 | 0 | 1 |
| 0 | 0 | 1 | 1 | 0 |
输出 − 图是连通的。
算法
traverse(u, visited)
输入 − 起始节点u和已访问节点,用于标记哪些节点已访问。
输出:遍历所有连接的顶点。
Begin
mark u as visited
for all vertex v, if it is adjacent with u, do
if v is not visited, then
traverse(v, visited)
done
EndisConnected(graph)
输入 − 图。
输出 − 如果图是连通的,则返回真。
Begin define visited array for all vertices u in the graph, do make all nodes unvisited traverse(u, visited) if any unvisited node is still remaining, then return false done return true End
示例代码
#include<iostream>
#define NODE 5
using namespace std;
int graph[NODE][NODE] = {{0, 1, 1, 0, 0},
{1, 0, 1, 1, 0},
{1, 1, 0, 1, 1},
{0, 1, 1, 0, 1},
{0, 0, 1, 1, 0}};
void traverse(int u, bool visited[]) {
visited[u] = true; //mark v as visited
for(int v = 0; v<NODE; v++) {
if(graph[u][v]) {
if(!visited[v])
traverse(v, visited);
}
}
}
bool isConnected() {
bool *vis = new bool[NODE];
//for all vertex u as start point, check whether all nodes are visible or not
for(int u; u < NODE; u++) {
for(int i = 0; i<NODE; i++)
vis[i] = false; //initialize as no node is visited
traverse(u, vis);
for(int i = 0; i<NODE; i++) {
if(!vis[i]) //if there is a node, not visited by traversal, graph is not connected
return false;
}
}
return true;
}
int main() {
if(isConnected())
cout << "The Graph is connected.";
else
cout << "The Graph is not connected.";
}输出
The Graph is connected.
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