技術標籤：日常練習演算法dfs圖解法c++

圖搜尋的API

起點（source）簡單記為s。
如圖marked()給出圖中v和s有沒有相連關係。

深度優先搜尋

#pragma once

#include"Graph.h"


class depthFirstSearch
{
public:
	depthFirstSearch(Graph& G, int s);
	
	int count() { return m_count; }
	bool marked(int v) { return m_marked->at(v); }

private:
	vector<
 
bool>* m_marked;//標記是否相連
	int m_count;//與source起點連通的頂點數，包括自己

	void dfs(Graph& G, int now);
};


depthFirstSearch::depthFirstSearch(Graph& G, int s)
{
	m_marked = new vector<bool>(G.V(), false);
	m_count = 0;
	dfs(G, s);
}

inline 
void depthFirstSearch::dfs(Graph& G, int now)
{
	m_marked-
 
>at(now) = true;
	m_count++;

	for (const auto &next : G.adj(now)) {
		if (!(*m_marked)[next]) {
			dfs(G, next);
		}
	}
}

廣搜

#pragma once
#include<queue>
#include"Graph.h"

class breadthFirstSearch {
public:
	breadthFirstSearch(Graph& G, int s);

	int count() { return m_count;
 
 }
	bool marked(int v) { return (*m_marked)[v]; }

private:
	vector<bool>* m_marked=nullptr;
	int m_count = 0;//相連通的節點，不包括自己
	void bfs(Graph& G, int now);
};


breadthFirstSearch::breadthFirstSearch(Graph& G, int s)
{
	m_marked = new vector<bool>(G.V(), false);
	m_count = 0;
	bfs(G, s);
}
inline void breadthFirstSearch::bfs(Graph& G, int now)
{
	queue<int> Q;
	(*m_marked)[now] = true;
	Q.push(now);
	while (!Q.empty()) {

		int v = Q.front();Q.pop();//從佇列中刪除下一頂點

		for (auto& w : G.adj(v)) {
			if (!(*m_marked)[w]) {//鄰接點未被標記
				m_marked->at(w) = true;//標記它，併入隊
				++m_count;//這裡是可變的，其他部分算固定框架
				Q.push(w);
			}
		}
	}

}

關於測試

圖的標頭檔案和資料檔案在這裡：從檔案讀取構建圖https://blog.csdn.net/qq_34890856/article/details/112938237

#include"depthFirstSearch.h"
//#include"breadthFirstSearch.h"

#define out(x) cout<<x<<" "
#define hh printf_s("\n")

void testDFS() {
	Graph G("data.txt");
	depthFirstSearch dfsG(G, 9);

	bool isconnected = dfsG.marked(0);
	int n = dfsG.count();

	out("9 0 connected ? "), out(isconnected), hh;
	out("how many connect to 9 ? "), out(n), hh;
	//out(G.toString());
}

int main() {
	testDFS();
	system("pause");
	return 0;
}