Cod sursa(job #1207114)

Utilizator 2dorTudor Ciurca 2dor Data 12 iulie 2014 12:04:44
Problema Algoritmul lui Dijkstra Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.46 kb
#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#include <cstring>
using namespace std;

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

typedef pair<int, int> cuplu;
const int MAXN = 50005;
const int INF = 0x3f3f3f3f;
int N, M;
int best[MAXN];
vector<cuplu> G[MAXN];

struct cmp {
    bool operator() (const cuplu A, const cuplu B) const {
        return A.second > B.second;
    }
};

priority_queue<cuplu, vector<cuplu>, cmp> PQ;

void Read() {
    fin >> N >> M;
    int a, b, c;
    for (int i = 0; i < M; ++i) {
        fin >> a >> b >> c;
        G[a].push_back( make_pair(b, c) );
    }
}

void Init() {
    memset(best, INF, sizeof(best));
    best[1] = 0;
    PQ.push( make_pair(1, 0) );
}

void Dijkstra() {
    do {
        cuplu node = PQ.top();
        PQ.pop();
        vector<cuplu>::iterator it;
        for (it = G[node.first].begin(); it != G[node.first].end(); ++it) {
            if (best[it->first] > best[node.first] + it->second) {
                best[it->first] = best[node.first] + it->second;
                PQ.push( make_pair(it->first, best[it->first]) );
            }
        }
    }while (!PQ.empty());
}

void Write() {
    for (int i = 2; i <= N; ++i) {
        fout << (best[i] == INF ? 0 : best[i]) << ' ';
    }fout << '\n';
}

int main() {
    Read();
    Init();
    Dijkstra();
    Write();
    fin.close();
    fout.close();
    return 0;
}