Cod sursa(job #2896222)

Utilizator MagnvsDaniel Constantin Anghel Magnvs Data 29 aprilie 2022 21:19:14
Problema Algoritmul lui Dijkstra Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.99 kb
#include <fstream>
#include <vector>

struct str{
    int x, y;
    str( int xnew, int ynew ) {
        x = xnew;
        y = ynew;
    }
};

std::vector < std::vector < str > > g;
std::vector < int > d;
std::vector < str > h;

void swap( str &x, str &y ) {
    str aux = x;
    x = y;
    y = aux;
}

void push( std::vector < str > &h, str x ) {
    h.push_back(x);
    int p = h.size();
    while ( p > 1 && h[p-1].y < h[p/2-1].y ) {
        swap(h[p-1], h[p/2-1]);
        p /= 2;
    }
}

void pop( std::vector < str > &h ) {
    swap(h.front(), h.back());
    h.pop_back();
    int p = 1;
    while ( ( p*2 <= int(h.size()) && h[p-1].y > h[p*2-1].y ) ||
        ( p*2+1 <= int(h.size()) && h[p-1].y > h[p*2].y ) ) {

        if ( p*2+1 <= int(h.size()) && h[p*2].y < h[p*2-1].y ) {
            swap(h[p-1], h[p*2]);
            p = p*2+1;
        } else {
            swap(h[p-1], h[p*2-1]);
            p = p*2;
        }
    }
}

int main( ) {
    std::ifstream fin("dijkstra.in");
    int n, m;
    fin >> n >> m;
    g.resize(n);
    for ( int i = 0; i < m; ++ i ) {
        int x, y, z;
        fin >> x >> y >> z;
        g[x-1].push_back(str(y-1, z));
    }
    fin.close();

    d.resize(n, -1);
    d[0] = 0;
    push(h, str(0, 0));
    while ( h.empty() == 0 ) {
        int x = h.front().x;
        int y = h.front().y;
        pop(h);
        if ( d[x] == y ) {
            for ( int i = 0; i < int(g[x].size()); ++ i ) {
                int xn = g[x][i].x;
                int yn = g[x][i].y;
                if ( d[xn] == -1 || d[xn] > d[x]+yn ) {
                    d[xn] = d[x]+yn;
                    push(h, str(xn, d[xn]));
                }
            }
        }
    }

    std::ofstream fout("dijkstra.out");
    for ( int i = 1; i < n; ++ i ) {
        if ( d[i] != -1 ) {
            fout << d[i] << " ";
        } else {
            fout << "0 ";
        }
    }
    fout << "\n";
    fout.close();
    return 0;
}