HDU_2586_How far away ？_MLE_floyd-优快云博客

本文链接：https://blog.youkuaiyun.com/cxy7tv/article/details/51155911

本文介绍了一种使用Floyd算法解决图中所有顶点对之间的最短路径问题的方法。通过具体的代码实现展示了如何构造邻接矩阵，并利用Floyd算法进行路径优化。

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#include<iostream>      
#include<sstream>      
#include<string>      
#include<vector>      
#include<list>      
#include<set>      
#include<map>      
#include<stack>      
#include<queue>      
#include<algorithm>      
#include<cmath>      
#pragma warning(disable:4996)      
using std::cin;
using std::cout;
using std::endl;
using std::stringstream;
using std::string;
using std::vector;
using std::list;
using std::pair;
using std::set;
using std::multiset;
using std::map;
using std::multimap;
using std::stack;
using std::queue;
int main()
{
	//freopen("input.txt", "r", stdin);
	//freopen("output.txt", "w", stdout);
	int T; cin >> T;
	while (T--)
	{
		int vertex, query;
		cin >> vertex >> query;
		vector<vector<int>>matrix(vertex, (vector<int>)vertex);
		for (int i = 0; i < vertex - 1; i++)
		{
			int first, second, weight;
			cin >> first >> second >> weight;
			matrix[first - 1][second - 1] = matrix[second - 1][first - 1] = weight;
		}
		for (int k = 0; k < vertex; k++)
		{
			for (int i = 0; i < vertex; i++)
			{
				for (int j = 0; j < vertex; j++)
				{
					if (i == j)
					{
						continue;
					}
					if (!matrix[i][j])
					{
						matrix[i][j] = matrix[i][k] + matrix[k][j];
					}
					else
					{
						matrix[i][j] = std::min(matrix[i][j], matrix[i][k] + matrix[k][j]);
					}
				}
			}
		}
		for (int i = 0; i < query; i++)
		{
			int first, second;
			cin >> first >> second;
			cout << matrix[first - 1][second - 1] << endl;
		}
	}
	return 0;
}