Cod sursa(job #2019330)

Utilizator bcrisBianca Cristina bcris Data 7 septembrie 2017 15:22:19
Problema Algoritmul lui Dijkstra Scor 0
Compilator cpp Status done
Runda Arhiva educationala Marime 1.82 kb
#include <stdio.h>
#include <vector>
#include <limits>
 
using namespace std;
 
#define NMAX 50005
#define INF 1 << 30 
 
int n, m;
int visited[NMAX], distances[NMAX], parent[NMAX];
int adjcency[NMAX][NMAX];

using namespace std;
 
 
void read() {
    scanf("%d %d\n", &n, &m);
    int a, b, c;
    for (int i = 0 ; i < m; i++) {
        scanf("%d %d %d\n", &a, &b, &c);
        adjcency[a][b] = c;
        adjcency[b][a] = c;
    }
}
 
void dijkstra(int begin_node) {
    visited[begin_node] = 1;
    for (int i = 1; i <= n; i++) {
        parent[i] = begin_node;
        if (adjcency[begin_node][i] != 0) 
    		distances[i] = adjcency[begin_node][i];
        else
    		distances[i] = INF;
    } 
 
    int nodes_visited = 1;
 
    while (nodes_visited < n) {
        int min_distance = INF;
        int next_node = -1;
        for (int i = 1; i <= n; i++) {
            if (visited[i] == 0 && distances[i] < min_distance) {
                min_distance = distances[i];
                next_node = i;
            }
        }
 
        if (next_node == -1)
            return;
        visited[next_node] = 1;
        nodes_visited++;
         
        for (int i = 1; i <= n; i++) {
        	if (adjcency[next_node][i] != 0) {
	            int neighbour = i;
	            int cost = adjcency[next_node][neighbour];
	            if (!visited[neighbour]) {
	                if (distances[next_node] + cost < distances[neighbour]) {
	                    distances[neighbour] = distances[next_node] + cost;
	                    parent[neighbour] = next_node;
	                }
	            }
        	}
        }   
    }       
}
 
int main() {
 
    freopen("dijkstra.in", "r", stdin);
    freopen("dijkstra.out", "w", stdout);
     
 
    read();
 
    dijkstra(1);
 
    for (int i = 2; i <= n; i++) {
        printf("%d ", distances[i]);
    }
    return 0;
}