Cod sursa(job #1993700)

Utilizator VladTiberiuMihailescu Vlad Tiberiu VladTiberiu Data 23 iunie 2017 16:36:01
Problema Algoritmul lui Dijkstra Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 2.52 kb
#include <bits/stdc++.h>

using namespace std;

#define DIM 10000
char buff[DIM];
int poz=0;

void cit(int &numar){
     numar = 0;
     while (buff[poz] < '0' || buff[poz] > '9')
          if (++poz == DIM)
               fread(buff,1,DIM,stdin),poz=0;
     while ('0'<=buff[poz] && buff[poz]<='9'){
          numar = numar*10 + buff[poz] - '0';
          if (++poz == DIM)
               fread(buff,1,DIM,stdin),poz=0;
     }
}

const int NMax = 50003;
const int INF = (1 << 30);

struct heap_stats{
    int value,graph_node;
};

heap_stats heap[NMax * 5];
int Size;

void go_up(int node){
    while(node > 1 && heap[node / 2].value > heap[node].value){
        swap(heap[node / 2], heap[node]);
        node /= 2;
    }
}
void go_down(int node){
    while((heap[node * 2].value < heap[node].value && node * 2 <= Size) ||
          (heap[node * 2 + 1].value < heap[node].value && node * 2 + 1 <= Size)){
        if(heap[node * 2].value < heap[node].value && node * 2 <= Size){
            swap(heap[node * 2], heap[node]);
            node *= 2;
        }else
        if(heap[node * 2 + 1].value < heap[node].value && node * 2 + 1 <= Size){
            swap(heap[node * 2 + 1],heap[node]);
            node = node * 2 + 1;
        }
    }
}
void insert_heap(int val,int graph_node){
    heap[++Size].value = val;
    heap[Size].graph_node = graph_node;
    go_up(Size);
}
void erase_heap(int node){
    swap(heap[node],heap[Size]);
    Size--;
    go_down(node);
}

int n,m,x,y,c;
int dist[NMax];
vector<pair<int,int> > G[NMax];

int main()
{
    freopen("dijkstra.in","r",stdin);
    freopen("dijkstra.out","w",stdout);
    cit(n);cit(m);
    for(int i = 1; i <= m; ++i){
        cit(x);cit(y);cit(c);
        G[x].push_back(make_pair(y,c));
    }

    for(int i = 1; i <= n; ++i){
        dist[i] = INF;
    }
    dist[1] = 0;

    insert_heap(0,1);

    while(Size){
        int current_distance = heap[1].value;
        int current_node = heap[1].graph_node;

        erase_heap(1);

        for(int i = 0; i < G[current_node].size(); ++i){
            int v = G[current_node][i].first;
            int cost = G[current_node][i].second;

            if(dist[v] > dist[current_node] + cost){
                dist[v] = dist[current_node] + cost;
                insert_heap(dist[v],v);
            }
        }
    }

    for(int i = 2; i <= n; ++i){
        if(dist[i] == INF)
            printf("0 ");
        else
            printf("%d ",dist[i]);
    }
    return 0;
}