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| // ConsoleApplication169.cpp : Этот файл содержит функцию "main". Здесь начинается и заканчивается выполнение программы.
//
#include "pch.h"
#include <iostream>
#include <iostream>
#include <vector>
#include <queue>
#include <climits>
using namespace std;
// Data structure to store graph edges
struct Edge {
int source, dest, weight;
public:
Edge(int s, int d, int w)
{
this->source = s;
this->dest = d;
this->weight = w;
}
};
// data structure to store heap nodes
struct Node {
int vertex, weight;
};
// class to represent a graph object
class Graph
{
public:
// construct a vector of vectors of Edge to represent an adjacency list
vector<vector<Edge>> adjList;
// Graph Constructor
Graph(vector<Edge> const &edges, int N)
{
// resize the vector to N elements of type vector<Edge>
adjList.resize(N);
// add edges to the undirected graph
for (Edge const &edge : edges)
{
// insert at end
adjList[edge.source].push_back(edge);
}
}
};
void print_route(vector<int> const &prev, int i)
{
if (i < 0)
return;
print_route(prev, prev[i]);
cout << i << " ";
}
// Comparison object to be used to order the heap
struct comp
{
bool operator()(const Node &lhs, const Node &rhs) const
{
return lhs.weight > rhs.weight;
}
};
// Run Dijkstra's algorithm on given graph
void shortestPath(Graph const& graph, int source, int N)
{
// create min heap and push source node having distance 0
priority_queue<Node, vector<Node>, comp> min_heap;
min_heap.push({ source, 0 });
// set infinite distance from source to v initially
vector<int> dist(N, INT_MAX);
// distance from source to itself is zero
dist[source] = 0;
// boolean array to track vertices for which minimum
// cost is already found
vector<bool> done(N, false);
done[0] = true;
// stores predecessor of a vertex (to print path)
vector<int> prev(N, -1);
// run till min_heap is not empty
while (!min_heap.empty())
{
// Remove and return best vertex
Node node = min_heap.top();
min_heap.pop();
// get vertex number
int u = node.vertex;
// do for each neighbor v of u
for (auto i : graph.adjList[u])
{
int v = i.dest;
int weight = i.weight;
// Relaxation step
if (!done[v] && (dist[u] + weight) < dist[v])
{
dist[v] = dist[u] + weight;
prev[v] = u;
min_heap.push({ v, dist[v] });
}
}
// marked vertex u as done so it will not get picked up again
done[u] = true;
}
for (int i = 1; i < N; ++i)
{
cout << "Path from vertex 0 to vertex " << i << " has minimum "
"cost of " << dist[i] << " and the route is [ ";
print_route(prev, i);
cout << "]\n";
}
}
// main function
int main()
{
setlocale(0, "");
int N, s, m;
cout << "Введите количество вершин " << endl;
cin >> N;
cout << "Введите количество ребер " << endl;
cin >> m;
cout << "Введите массив ребер " << endl;
// initialize edges as per above diagram // если ребро без направления - нужно писать его дважды
vector<Edge> edges; // хочу вот это заменить на ввод вручную, а оно не хочет
for (int i = 0; i < m; i++)
{
int a, b, c;
scanf_s("%d - %d - %d", &a, &b, &c);
if (edges.capacity() > i)
edges.push_back(*(new Edge(a, b, c)));
else
edges.resize(i + 1, *(new Edge(a, b, c)));
}
// construct graph
Graph graph(edges, N);
cout << "Введите начальную вершину " << endl;
cin >> s;
// Number of nodes in the graph
shortestPath(graph, s, N);
return 0;
/*{0, 1, 10},
{0, 4, 3},
{1, 2, 2},
{1, 4, 4},
{2, 3, 9},
{3, 2, 7},
{4, 1, 1},
{4, 2, 8},
{4, 3, 2}*/
} |
(
Сообщение от Yavorsky
