Cod sursa(job #1509415)

Utilizator angelaAngela Visuian angela Data 23 octombrie 2015 20:33:44
Problema Algoritmul lui Dijkstra Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.24 kb
#include <fstream>
#include <set>
#include <algorithm>
#include <vector>
#include <queue>
using namespace std;

ifstream fin("dijkstra.in");
ofstream fout("dijkstra.out");

struct Pair {
	int dist, nod;
	
	bool operator < (const Pair& p) const
	{
		return dist > p.dist;
	}
};

using VI = vector<int>;
using VVI = vector<VI>;
using PII = pair<int, int>;

const int Inf = 0x3f3f3f3f;
VI d;     // sirul distantelor minime
int n, m;
vector<vector<PII>> G;

void Read();
void Dijkstra(VI& d, int S);
void Write();

int main()
{
	Read();
	Dijkstra(d, 1);
	
	Write();
	
	fin.close();
	fout.close();
}

void Dijkstra(VI& d, int S)
{
	priority_queue<Pair> Q;
	d = VI(n + 1, Inf);
	d[S] = 0;
	Q.push({0, S});
	int x, dx,  y, w; 
	
	while ( !Q.empty() )
	{
		x = Q.top().nod;
		dx = Q.top().dist;
		Q.pop();
		if ( d[x] < dx )
			continue;
		for (const auto& e : G[x])
		{
			y = e.first; w = e.second;
			
			if ( d[y] > d[x] + w )
			{
				d[y] = d[x] + w;
				Q.push({d[y], y});
			}
		}
	}
}

void Read()
{
	fin >> n >> m;
	G = vector<vector<PII>>(n + 1);
	
	for (int i = 1, x, y, w; i <= m; ++i)
	{
		fin >> x >> y >> w;
		G[x].push_back({y, w});
	}	 
}


void Write()
{
	for (int i = 2; i <= n; ++i)
		if ( d[i] < Inf )
			fout << d[i] << ' ';
		else
			fout << 0 << ' ';
	
}