Cod sursa(job #2705420)

Utilizator linxulRazvan Gap linxul Data 12 februarie 2021 16:19:15
Problema Algoritmul lui Dijkstra Scor 10
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.72 kb
#include <bits/stdc++.h>
#define mp make_pair 
#define oo 0x3f3f3f3f
using namespace std;

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

int n, m;
vector<pair<int ,int > > g[50001];
int d[50001];
bool inq[50001];
int q[500011];
int sz;

void HeapUp(int i)
{
    int minn = i;
    int p = i / 2;
    if(p > 0 && d[q[p]] > d[q[minn]])
    {
        swap(q[p], q[minn]);
        HeapUp(i);
    }
}

void HeapDown(int i)
{
    int minn = i;
    int st = 2 * i;
    int dr = 2 * i + 1;
    if(st <= n && d[q[st]] < d[q[minn]])
        minn = st;
    if(dr <= n && d[q[dr]] < d[q[minn]])
        minn = dr;
    if(minn != i)
    {
        swap(q[i], q[minn]);
        HeapDown(minn);
    }
}

inline void push(int val)
{
    q[++sz] = val;
    HeapUp(sz);
}
inline void pop()
{
    q[1] = q[sz--];
    HeapDown(1);
}

void Dijkstra(int nod)
{
    memset(d, oo, sizeof(d));
    push(nod);
    inq[nod] = true;
    d[nod] = 0;
    while(sz > 0)
    {
        nod = q[1];
        pop();
        inq[nod] = false;
        for(auto i : g[nod])
        {
            if( d[i.second] > d[nod] + i.first)
            {
                d[i.second] = d[nod] + i.first;
                if(!inq[i.second]){
                    push(i.second);
                    inq[i.second] = 1;
                }
            }
        }
    }
}

int main()
{
    int x, y, w;
    fin >> n >> m;
    for(int i = 1; i <= m; i++)
    {
        fin >> x >> y >> w;
        g[x].push_back(mp(w, y));
    }
    Dijkstra(1);
    for(int i = 2; i <= n; i++){
        if(d[i] != oo)
        fout << d[i] << " ";
        else fout << "0 ";
    }
    fin.close();
    fout.close();
    return 0;
}