c++实现dijskstra算法

图

我一开始写成了最小生成树的代码，最小生成树一直在选最小的那条边，对每个节点来说，它到原点的距离不一定是最近的。

代码

#include
using namespace std;
#include
#include

class Node
{
public:
	Node(int name):_name(name){}

	void set_father(int father) {
		_father = father;
	}
	int get_father()
	{
		return _father;
	}

private:
	int _name;
	int _father = -1;
};

int main()
{
	const int numNode = 7;
	int weights[numNode + 1][numNode+1];
	for (int i = 0; i < numNode + 1; ++i)
	{
		for (int j = 0; j < numNode + 1; ++j)
		{
			if (i == j) weights[i][j] = 0;
			else weights[i][j] = INT_MAX / 2 - 1;
		}
	}
	weights[1][2] = 12;
	weights[2][1] = 12;

	weights[2][3] = 10;
	weights[3][2] = 10;

	weights[3][4] = 3;
	weights[4][3] = 3;

	weights[4][5] = 4;
	weights[5][4] = 4;

	weights[5][6] = 2;
	weights[6][5] = 2;

	weights[6][7] = 9;
	weights[7][6] = 9;

	weights[1][7] = 14;
	weights[7][1] = 14;

	weights[1][6] = 16;
	weights[6][1] = 16;

	weights[6][2] = 7;
	weights[2][6] = 7;

	weights[3][5] = 5;
	weights[5][3] = 5;

	weights[5][7] = 8;
	weights[7][5] = 8;

	Node one(1);
	Node two(2);
	Node three(3);
	Node four(4);
	Node five(5);
	Node six(6);
	Node seven(7);

	list<int> visited_nodes;

	// 求各点到点4的最短距离，并输出最短路径
	int distanceTo4[numNode + 1];
	bool visited[numNode + 1];
	
	for (int i = 0; i < numNode + 1; ++i) // 最短距离初始化
	{
		distanceTo4[i] = INT_MAX / 2 - 1;
	}
	distanceTo4[4] = 0;
	

	for (int i = 0; i < numNode + 1; ++i) // 是否已经访问初始化
	{
		visited[i] = false;
	}
	visited[4] = true;

	int updateIndex = 4;
	visited_nodes.push_back(updateIndex);
	
	while (visited_nodes.empty() == false)
	{
		int preUpdateIndex = visited_nodes.front();
		visited_nodes.pop_front();

		for (int i = 1; i < numNode + 1; ++i)
		{
			if (weights[i][preUpdateIndex] < 1000) 
			{
				// 说明是preUpdateIndex的邻居
				int tmpDistance = min(
					distanceTo4[i],
					distanceTo4[preUpdateIndex] + weights[i][preUpdateIndex]);
				if (tmpDistance == (distanceTo4[preUpdateIndex] + weights[i][preUpdateIndex]) && distanceTo4[i]!=tmpDistance)
				{
					// 说明更新了
					switch (i)
					{
					case 1:
					{
						one.set_father(preUpdateIndex);
					}break;
					case 2:
					{
						two.set_father(preUpdateIndex);
					}break;
					case 3:
					{
						three.set_father(preUpdateIndex);
					}break;
					case 4:
					{
						four.set_father(preUpdateIndex);
					}break;
					case 5:
					{
						five.set_father(preUpdateIndex);
					}break;
					case 6:
					{
						six.set_father(preUpdateIndex);
					}break;
					case 7:
					{
						seven.set_father(preUpdateIndex);
					}break;
					default: break;
					}
				
					visited_nodes.push_back(i);
				}

				distanceTo4[i] = tmpDistance;
			}

		}

	}

	for (int i = 1; i < numNode + 1; ++i)
	{
		cout << distanceTo4[i] << " ";
	}
	cout << endl;
	
	// 打印从1->4的最短路径
	vector<int> path14;
	path14.push_back(1);
	Node *node;
	node = &one;
	while (true)
	{
		int index = node->get_father();	
		if (index == -1) break;

		path14.push_back(index);
		
		switch (index)
		{
		case 1:
			node = &one; break;
		case 2:
			node = &two; break;
		case 3:
			node = &three; break;
		case 4:
			node = &four; break;
		case 5:
			node = &five; break;
		case 6:
			node = &six; break;
		case 7:
			node = &seven; break;
		default: break;
		}
		
	}
	
	for (int i = 0; i < path14.size(); ++i)
	{
		if (i != 0) {
			cout << "->" << path14[i];
		}
		else {
			cout << path14[i];
		}
	}
	cout << endl;


	return 0;
}
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结果