Dijkstra shortest path algorithm implementation code

• 2020-04-02 02:04:09
• OfStack

Dijkstra's shortest path algorithm is calculated based on the shortest path of the precursor vertex. Generally speaking, it is relatively simple. The following is the code:

``````
#include <iostream>
#include <vector>
#include <limits>
void shortestpath( const std::vector <std::vector< short> >& paths, int from, std::vector< short>& path){
std:: vector<bool> flags(paths.size(), false);
std:: vector<short> distance(paths.size(), 0);
path.resize(paths.size(), 0);
for(size_t i = 0; i != paths.size(); ++i){
distance[i] = paths[from][i];
}
flags[from] = 1;
int min, pos;
for(size_t i = 1; i != paths.size(); ++i){
pos = -1;
min = std:: numeric_limits<short>::max();
for(size_t j = 0; j != paths.size(); ++j){
if(!flags[j] && distance[j] < min){
min = distance[j];
pos = j;
}
}
if(pos == -1)
break;
flags[pos] = true;
for(size_t j = 0; j != paths.size(); ++j){
if(!flags[j] && paths[pos][j] != 0
&& paths[pos][j] < std::numeric_limits <int>:: max()
&& min+paths[pos][j] < distance[j]){
distance[j] = min + paths[pos][j];
path[j] = pos;
}
}
}
for(size_t i = 0; i != distance.size(); ++i){
std::cout << distance[i] << " " << std::flush;
}
std::cout << std:: endl;
}
int main(){
std::cout << " Please enter the number of vertices: " << std::flush;
int sum; std::cin >> sum;
std:: vector<std::vector <short> > paths;
for(int i = 0; i != sum; ++i){
paths.push_back(std:: vector<short>(sum, std::numeric_limits< short>::max()));
paths[i][i] = 0;
}
std::cout << " Please enter the number of edges: " << std::flush;
std::cin >> sum;
int vi, vj, weight;
for(int i = 0; i != sum; ++i){
std::cin >> vi >> vj >> weight;
paths[vi][vj] = weight;
paths[vj][vi] = weight;
}
std:: vector<short> path;
shortestpath(paths, 0, path);
std::cout << " The result of the nearest path is: " << std::flush;
for(size_t i = 0; i != path.size(); ++i){
std::cout << path[i] << " " << std::flush;
}
std::cout << std:: endl;
return 0;
}
``````

Related articles: