Cod sursa(job #1995647)

Utilizator Horia14Horia Banciu Horia14 Data 28 iunie 2017 18:47:19
Problema Algoritmul lui Dijkstra Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.97 kb
#include<cstdio>
#define MAX_N 50000
#define oo 2000000000
using namespace std;

struct nod
{
    int val, c;
    nod* next;
};

int d[MAX_N + 1], h[MAX_N + 1], pos[MAX_N + 1], n, m, k;
nod* L[MAX_N + 1];

inline void InsertNode(int x, int y, int c)
{
    nod* elem = new nod;
    elem->val = y;
    elem->c = c;
    elem->next = L[x];
    L[x] = elem;
}

inline void Swap(int i, int j)
{
    int x;
    x = h[i];
    h[i] = h[j];
    h[j] = x;
    x = pos[h[i]];
    pos[h[i]] = pos[h[j]];
    pos[h[j]] = x;
}

void heapdown(int i)
{
    int l, r;
    if(2*i > k) return;
    l = d[h[2*i]];
    if(2*i + 1 <= k)
        r = d[h[2*i+1]];
    else r = l + 1;
    if(l < r)
    {
        if(d[h[i]] <= l) return;
        Swap(i,2*i);
        heapdown(2*i);
    }
    else
    {
        if(d[h[i]] <= r) return;
        Swap(i,2*i+1);
        heapdown(2*i+1);
    }
}

void heapup(int i)
{
    if(d[h[i/2]] <= d[h[i]]) return;
    Swap(i,i/2);
    heapup(i/2);
}

int main()
{
    int i, x, y, c, Nod;
    nod* p;
    FILE *fin, *fout;
    fin = fopen("dijkstra.in","r");
    fout = fopen("dijkstra.out","w");
    fscanf(fin,"%d%d",&n,&m);
    for(i=1; i<=m; i++)
    {
        fscanf(fin,"%d%d%d",&x,&y,&c);
        InsertNode(x,y,c);
    }
    fclose(fin);
    for(i=1; i<=n; i++)
    {
        d[i] = oo;
        h[i] = i;
        pos[i] = i;
    }
    d[1] = 0;
    d[0] = -1;
    k = n;
    for(i=1; i<=n; i++)
    {
        Nod = h[1];
        Swap(1,k);
        k--;
        heapdown(1);
        p = L[Nod];
        while(p != NULL)
        {
            if(d[p->val] > d[Nod] + p->c)
            {
                d[p->val] = d[Nod] + p->c;
                heapup(pos[p->val]);
            }
            p = p->next;
        }
    }
    for(i=2; i<=n; i++)
        if(d[i] != oo)
            fprintf(fout,"%d ",d[i]);
    else fprintf(fout,"0 ");
    fprintf(fout,"\n");
    fclose(fout);
    return 0;
}