Cod sursa(job #491356)

Utilizator claudiumihailClaudiu Mihail claudiumihail Data 11 octombrie 2010 00:14:39
Problema Algoritmul lui Dijkstra Scor 90
Compilator cpp Status done
Runda Arhiva educationala Marime 4.4 kb
#include<fstream>
#include<iostream>
#include<vector>
using namespace std;

#define INF 0x17D7841

struct Compare;
struct Update;
template<typename T, class Compare, class Update> class CHeap;

typedef vector<vector<pair<unsigned short,int> > > Graph;
typedef CHeap<pair<int,unsigned short>,Compare,Update> Heap;

template<typename T, class Compare, class Update>
class CHeap
{
private:
	int size;
	Compare com;
	Update upd;
	vector<int> vIndexes;
	vector<T> vHeap;
	
	inline void swap(const int first, const int second)
	{
		upd(vHeap,vIndexes,first,second);
		T aux;
		aux=vHeap[first];
		vHeap[first]=vHeap[second];
		vHeap[second]=aux;
	}
	
	void siftUp(int index)
	{
		int parent=(index-1-!(index%2))>>1;
		while(parent>=0 && com(vHeap[index],vHeap[parent]))
		{
			swap(parent,index);
			index=parent;
			parent=(index-1-!(index%2))>>1;
		}
	}
	
	void siftDown(int index)
	{
		int child1,child2;
		bool ord=true;
		child1=(index<<1)+1;
		child2=(index+1)<<1;
		while(ord && child1<size)
		{
			ord=false;
			if(child1<size && child2<size)
			{
				if(com(vHeap[child1],vHeap[child2]))
				{
					if(com(vHeap[child1],vHeap[index]))
					{
						swap(child1,index);
						index=child1;
						ord=true;
					}
				}
				else if(com(vHeap[child2],vHeap[index]))
				{
					swap(child2,index);
					index=child2;
					ord=true;
				}
			}
			else if(child1<size)
			{
				if(com(vHeap[child1],vHeap[index]))
				{
					swap(child1,index);
					index=child1;
					ord=true;
				}
			}
			child1=(index<<1)+1;
			child2=(index+1)<<1;
		}
	}
public:

	CHeap() : size(0)
	{}
	
	CHeap(const Compare& comm, const Update& updd) : size(0), com(comm), upd(updd)
	{}
	
	void insert(const T& val)
	{
		vHeap.push_back(val);
		size++;
		vIndexes.push_back(size-1);
		siftUp(size-1);
	}
	
	void modify(const int pos, const T& val)
	{
		if(com(vHeap[pos],val))
			vHeap[pos]=val;
		else
			vHeap[pos]=val;
		siftUp(pos);
	}
	
	void remove(const int pos)
	{
		swap(pos,--size);
		vHeap.pop_back();
		siftDown(pos);
	}
	
	const T& getElement(const int pos) const
	{
		return vHeap[pos];
	}
	
	int getPos(const int time) const
	{
		return vIndexes[time];
	}
	
	bool empty() const
	{
		return (size==0);
	}
	
	void print()
	{
		for(unsigned int i=0; i<vHeap.size(); ++i)
		{
			cout<<"("<<vHeap[i].first<<" "<<vHeap[i].second<<") ";
		}
		cout<<endl;
	}
};

struct Compare
{
	bool operator() (const pair<int,int>& a, const pair<int,int>& b) const
	{
		return a.first<b.first;
	}
};

struct Update
{
	void operator() (const vector<pair<int,unsigned short> >& vHeap,
					 vector<int>& vIndexes, 
					 const int first, const int second) const
	{
		vIndexes[vHeap[first].second]=second;
		vIndexes[vHeap[second].second]=first;
	}
};

void Dijkstra(Graph& graph, const int n, const unsigned short s, int* dist)
{
	Compare com;
	Update upd;
	Heap heap(com,upd);
	
	for(int i=0; i<n; ++i)
	{
		if(i==s)
		{
			heap.insert(make_pair(0,i));
			dist[i]=0;
		}
		else
		{
			heap.insert(make_pair(INF,i));
			dist[i]=INF;
		}
	}
	
	//heap.print();
	
	while(!heap.empty())
	{
		const pair<int,unsigned short> node=heap.getElement(0);
		dist[node.second]=node.first;
		heap.remove(0);
		if(node.first==INF)
			break;
		for(int i=0; i<(int)graph[node.second].size(); ++i)
		{
			const int alt=dist[node.second]+graph[node.second][i].second;
			if(alt<dist[graph[node.second][i].first])
			{
				dist[graph[node.second][i].first]=alt;
				heap.modify(heap.getPos(graph[node.second][i].first),make_pair(alt,graph[node.second][i].first));
			}	
		}
	}
}

int main()
{
	int n,m,a,b,c,*dist;
	fstream fin("dijkstra.in", fstream::in);
	fstream fout("dijkstra.out", fstream::out);
	
	Graph graph;
	
	fin>>n>>m;
	graph.resize(n+2);
	dist=new int[n+2];
	
	for(int i=0; i<m; ++i)
	{
		fin>>a>>b>>c;
		//cout<<a<<" "<<b<<" "<<c<<"\n";
		graph[a-1].push_back(make_pair(b-1,c));
	}
	
	Dijkstra(graph,n,0,dist);
	for(int i=1; i<n; ++i)
	{
		if(dist[i]==INF)
			fout<<0<<" ";
		else
			fout<<dist[i]<<" ";
	}
	fout<<endl;
	
	
	/*for(int i=0; i<5; ++i)
		heap.insert(make_pair(5-i,i));
	heap.print();
	
	heap.modify(3,make_pair(-1,0));
	heap.print();
	
	heap.remove(heap.getPos(0));
	heap.print();
	heap.remove(heap.getPos(3));
	heap.print();*/
	
	delete dist;
	fin.close();
	fout.close();
	return 0;
}