Cod sursa(job #1479948)

Utilizator bpalaniciPalanici Bogdan bpalanici Data 1 septembrie 2015 18:19:20
Problema Algoritmul lui Dijkstra Scor 90
Compilator cpp Status done
Runda Arhiva educationala Marime 2.27 kb
#include <bits/stdc++.h>
#define father(x) ( (x) >> 1 )
#define left_son(x) ( (x) << 1)
#define right_son(x) ( ((x) << 1) + 1 )
using namespace std;

typedef int H[50005];

const int inf = 0x3f3f3f3f;
int n, m;
int dist[50005];
H Heap;
vector < pair <int, int> > graf[50005];

void downHeap(H Heap, int n, int k)
{
    int son = 1;
    for (; son;)
    {
        son = 0;
        if (left_son(k) <= n)
        {
            son = left_son(k);
            if (right_son(k) <= n && dist[ Heap[left_son(k)]] > dist[ Heap[right_son(k)]])
            son = right_son(k);
        }
        if (dist[ Heap[son]] > dist[ Heap[k]])
            son = 0;
        if (son)
            swap(Heap[k], Heap[son]);
            k = son;
    }
}

void upHeap(H Heap, int n, int k)
{
    for (; k > 1;)
    {
        if (dist[ Heap[father(k)]] > dist[ Heap[k]])
            swap(Heap[k], Heap[father(k)]);
        else return;
        k = father(k);
    }
}

void insert(H Heap, int &n, int x)
{
    n++;
    Heap[n] = x;
    upHeap(Heap, n, n);
}

void remove(H Heap, int &n, int k)
{
    swap(Heap[k], Heap[n]);
    Heap[n] = 0;
    n--;
    if (k > 1 && (dist[ Heap[k]] < dist[ Heap[father(k)]]))
        upHeap(Heap, n, k);
    else downHeap(Heap, n, k);
}

void dijkstra()
{
    memset(dist, inf, sizeof dist);
    memset(Heap, 0, sizeof Heap);
    Heap[0] = Heap[1] = 1;
    dist[1] = 0;
    while (Heap[0])
    {
        int nod = Heap[1];
        remove(Heap, Heap[0], 1);
        for (vector < pair <int, int> >::iterator it = graf[nod].begin(); it != graf[nod].end(); it++)
        {
            int next_nod = it->first, next_dist = it->second;
            if (dist[next_nod] > dist[nod] + next_dist)
            {
                dist[next_nod] = dist[nod] + next_dist;
                insert(Heap, Heap[0], next_nod);
            }
        }
    }
}

int main()
{
    freopen("dijkstra.in", "r", stdin);
    freopen("dijkstra.out", "w", stdout);
    scanf("%d %d", &n, &m);
    for (int i = 1, a, b, c; i <= m; i++)
        scanf("%d %d %d", &a, &b, &c),
        graf[a].push_back(make_pair(b, c));

    dijkstra();

    for (int i = 2; i <= n; i++)
        printf("%d ", dist[i] == inf ? 0 : dist[i]);
    return 0;
}   ///min-Heap