Cod sursa(job #1128581)

Utilizator 2dorTudor Ciurca 2dor Data 27 februarie 2014 17:42:43
Problema Algoritmul lui Dijkstra Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.45 kb
#include <fstream>
#include <vector>
#include <queue>
#include <cstring>
using namespace std;

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

const int MAXN = 50005;
const int INF = 0x3f3f3f3f;
typedef pair<int, int> cuplu;

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

int N, M;
int best[MAXN];
vector<cuplu> G[MAXN];
priority_queue< cuplu, vector<cuplu>, cmp > PQ;
bool marked[MAXN];

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 Dijkstra() {
    PQ.push(make_pair(1, 0));
    do {
        int node = PQ.top().first;
        PQ.pop();
        marked[node] = true;
        vector<cuplu>::iterator it;
        for (it = G[node].begin(); it != G[node].end(); ++it) {
            if (best[it->first] > best[node] + it->second) {
                best[it->first] = best[node] + it->second;
                if (!marked[it->first])
                    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]) << ' ';
}

int main() {
    Read();
    memset(best, INF, sizeof(best));
    best[1] = 0;
    Dijkstra();
    Write();
    fin.close();
    fout.close();
    return 0;
}