Cod sursa(job #989280)

Utilizator Cosmin1490Balan Radu Cosmin Cosmin1490 Data 25 august 2013 13:54:38
Problema Algoritmul lui Dijkstra Scor 60
Compilator cpp Status done
Runda Arhiva educationala Marime 2.7 kb
#include <vector>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <queue>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <fstream>
using namespace std;
  
const string file = "dijkstra";
  
const string infile = file + ".in";
const string outfile = file + ".out";


const int INF = 0x3f3f3f3f;
int N, M;
vector<vector<pair<int, int> > > G;
vector<int> dist;

vector<int> heap;
vector<int> poz;


int lSon(int i)
{
	return i * 2;
}

int rSon(int i)
{
	return i * 2 + 1;
}

int parent(int i)
{
	return i / 2;
}

void swapHeap(int a, int b)
{
	int aux = heap[a];
	heap[a] = heap[b];
	heap[b] = aux;

	poz[heap[a]] = a;
	poz[heap[b]] = b;
}

void upHeap(int i)
{
	while(i > 1 && dist[heap[i]] < dist[heap[parent(i)]])
	{
		swapHeap(i, parent(i));
		i = parent(i);
	}
}

void downHeap(int i)
{
	int min = i;

	while(true)
	{
		if(lSon(i) >= (heap.size() - 1) && dist[min] > dist[lSon(i)])
			min = lSon(i);
		if(rSon(i) >= (heap.size() - 1)&& dist[min] > dist[rSon(i)])
			min = rSon(i);

		if(min == i)
			break;
		swapHeap(i, min);
		i = min;
	}

}

int topHeap()
{
	return heap[1];
}

void popHeap()
{
	swapHeap(1, heap.size() - 1);
	poz[heap[heap.size() - 1]] = 0;
	heap.pop_back();
	downHeap(1);
}

void pushHeap(int i)
{
	
	heap.push_back(i);
	poz[i] = heap.size() - 1;
	upHeap(heap.size() - 1);
}

void Dijkstra()
{
	poz.resize(N + 1);
	heap.reserve(N + 1);
	heap.push_back(0);
	dist.resize(N + 1, INF);
	dist[1] = 0;
	pushHeap(1);

	while(heap.size() > 1)
	{
		int current = topHeap();
		popHeap();

		for(vector<pair<int, int> >::iterator itr = G[current].begin();
			itr != G[current].end();
			itr++)
		{
			if(dist[itr->first] > dist[current] + itr->second)
			{
				dist[itr->first] = dist[current] + itr->second;
				if(poz[itr->first] == 0)
				{
					pushHeap(itr->first);
				}
				else
				{
					upHeap(poz[itr->first]);
				}
				
			}
		}
	}

}

int main()
{
	fstream fin(infile.c_str(), ios::in);
	fin >> N >> M;

	G.resize(N + 1);

	for(int i = 0; i < M; i++)
	{
		int x, y, c;
		fin >> x >> y >> c;
		G[x].push_back(make_pair(y, c));
	}


	Dijkstra();

	fin.close();

	fstream fout(outfile.c_str(), ios::out);
	for(int i = 2; i <= N; i++)
	{
		fout << ((dist[i] == INF) ? 0 : dist[i]) << " ";
	}
	fout << "\n";
	fout.close();
}