Cod sursa(job #2589142)

Utilizator k2e0e0w3qDumitrescu Gheorghe k2e0e0w3q Data 25 martie 2020 20:32:02
Problema Algoritmul Bellman-Ford Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 3.84 kb
#include <bits/stdc++.h>
#define N 50001
#define INF 0x3F3F3F3F
using namespace std;

bitset <N> enqueue;
vector <pair <int, int>> G[N];
array <int, N> dist, ct;
class cmp {
public:
    bool operator () (const int &a, const int &b) {
        return dist[a]>dist[b];
    }
};


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;
    }
};

class OutParser {
private:
    FILE *fout;
    char *buff;
    int sp;

    void write_ch(char ch) {
        if (sp == 50000) {
            fwrite(buff, 1, 50000, fout);
            sp = 0;
            buff[sp++] = ch;
        } else {
            buff[sp++] = ch;
        }
    }

public:
    OutParser(const char* name) {
        fout = fopen(name, "w");
        buff = new char[50000]();
        sp = 0;
    }

    ~OutParser() {
        fwrite(buff, 1, sp, fout);
        fclose(fout);
    }

    OutParser& operator << (int vu32) {
        if (vu32 < 0)
            write_ch('-'),
            vu32*=-1;
        if (vu32 <= 9) {
            write_ch(vu32 + '0');
        } else {
            (*this) << (vu32 / 10);
            write_ch(vu32 % 10 + '0');
        }
        return *this;
    }

    OutParser& operator << (long long vu64) {
        if (vu64 <= 9) {
            write_ch(vu64 + '0');
        } else {
            (*this) << (vu64 / 10);
            write_ch(vu64 % 10 + '0');
        }
        return *this;
    }

    OutParser& operator << (char ch) {
        write_ch(ch);
        return *this;
    }

    OutParser& operator << (const char *ch) {
        while (*ch) {
            write_ch(*ch);
            ++ch;
        }
        return *this;
    }
};

int main () {
    InParser fin ("bellmanford.in");
    OutParser fout ("bellmanford.out");
    ios::sync_with_stdio(false);

    int n, m, i, j, c;
    fin >> n >> m;
    for (; m; m--) {
        fin >> i >> j >> c;
        G[i].push_back(make_pair(j, c));
    }

    bool stop=0;
    dist.fill(INF);
    priority_queue <int, vector <int>, cmp> Q;
    Q.push(1);
    enqueue[1]=ct[1]=1;
    dist[1]=0;
    while (!Q.empty() && !stop) {
        auto save=Q.top();
        Q.pop();
        enqueue[save]=0;

        for (auto it: G[save])
            if (dist[it.first]>dist[save]+it.second) {
                dist[it.first]=dist[save]+it.second;
                if (!enqueue[it.first]) {
                    Q.push(it.first);
                    enqueue[it.first]=1;
                    ct[it.first]++;
                    if (ct[it.first]==n)
                        stop=1;
                }
            }
    }

    if (!stop)
        for (i=2; i<=n; i++)
            fout << dist[i] << ' ';
    else
        fout << "Ciclu negativ!";
    return 0;
}