Cod sursa(job #3166823)

Utilizator andu9andu nita andu9 Data 9 noiembrie 2023 17:39:15
Problema Algoritmul lui Dijkstra Scor 60
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 2.26 kb
#include <fstream>
#include <vector>
#include <climits>
#include <utility>
#include <queue>

class InParser {
private:
	FILE *fin;
	char *buff;
	int sp;

	char read_ch() {
		++sp;
		if (sp == 4096) {
			sp = 0;
			fread(buff, 1, 4096, fin);
		}
		return buff[sp];
	}

public:
	InParser(const char* nume) {
		fin = fopen(nume, "r");
		buff = new char[4096]();
		sp = 4095;
	}

	InParser& operator >> (int &n) {
		char c;
		while (!isdigit(c = read_ch()) && c != '-');
		int sgn = 1;
		if (c == '-') {
			n = 0;
			sgn = -1;
		} else {
			n = c - '0';
		}
		while (isdigit(c = read_ch())) {
			n = 10 * n + c - '0';
		}
		n *= sgn;
		return *this;
	}

	InParser& operator >> (long long &n) {
		char c;
		n = 0;
		while (!isdigit(c = read_ch()) && c != '-');
		long long sgn = 1;
		if (c == '-') {
			n = 0;
			sgn = -1;
		} else {
			n = c - '0';
		}
		while (isdigit(c = read_ch())) {
			n = 10 * n + c - '0';
		}
		n *= sgn;
		return *this;
	}
};

InParser fin("dijkstra.in");
std::ofstream fout("dijkstra.out");

const int INF = INT_MAX;

struct Min {
    int nod, cost;
};

struct compare {
    bool operator () (Min & a, Min & b) {
        return a.cost < b.cost;
    }
};

int main () {
    int n, m; fin >> n >> m;
    std::vector<int> dist(n, INF);

    std::priority_queue<Min, std::vector<Min>, compare> heap;

    std::vector<std::vector<Min>> graph(n, std::vector<Min> ());

    while (m > 0) {
        int u, v, c; fin >> u >> v >> c; u -= 1, v -= 1;
        graph[u].emplace_back (Min {v, c});
        m -= 1;
    }


    dist[0] = 0;
    heap.push (Min {0, 0});
    while (!heap.empty ()) {
        int intermediary = heap.top().nod;
        int distance = heap.top ().cost;
        heap.pop ();

        for (int i = 0; i < (int) graph[intermediary].size (); i += 1) {
            int nod = graph[intermediary][i].nod;
            int Dist = graph[intermediary][i].cost;

            if (dist[nod] > dist[intermediary] + Dist) {
                dist[nod] = dist[intermediary] + Dist;
                heap.push (Min {nod, dist[nod]});
            }
        }
    }

    for (int i = 1; i < (int) dist.size (); i += 1)
        fout << (dist[i] != INF ? dist[i] : 0) << ' ';
    return 0;
}