Cod sursa(job #2165305)

Utilizator Horia14Horia Banciu Horia14 Data 13 martie 2018 11:47:40
Problema BFS - Parcurgere in latime Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.57 kb
#include<cstdio>
#include<vector>
#include<queue>
#include<cctype>
#define MAX_N 100000
#define BUF_SIZE 1 << 19
using namespace std;

vector<int>g[MAX_N + 1];
queue<int>q;
int dist[MAX_N + 1], n, m, S, pos = BUF_SIZE;
char buf[BUF_SIZE];

inline char getChar(FILE *fin) {
    if(pos == BUF_SIZE) {
        fread(buf,1,BUF_SIZE,fin);
        pos = 0;
    }
    return buf[pos++];
}

inline int read(FILE *fin) {
    int res = 0;
    char c;
    do {
        c = getChar(fin);
    }while(!isdigit(c));
    do {
        res = 10*res + c - '0';
        c = getChar(fin);
    }while(isdigit(c));
    return res;
}

void readGraph() {
    int x, y;
    FILE *fin = fopen("bfs.in","r");
    n = read(fin); m = read(fin); S = read(fin);
    for(int i = 0; i < m; i++) {
        x = read(fin); y = read(fin);
        g[x].push_back(y);
    }
    fclose(fin);
}

void BFS(int node) {
    int Node;
    for(int i = 1; i <= n; i++)
        dist[i] = -1;
    dist[node] = 0;
    q.push(node);
    while(!q.empty()) {
        Node = q.front();
        q.pop();
        for(vector<int>::iterator it = g[Node].begin(); it != g[Node].end(); it++) {
            if(dist[*it] == -1) {
                dist[*it] = dist[Node] + 1;
                q.push(*it);
            }
        }
    }
}

void printDistances() {
    FILE *fout = fopen("bfs.out","w");
    for(int i = 1; i <= n; i++)
        fprintf(fout,"%d ",dist[i]);
    fprintf(fout,"\n");
    fclose(fout);
}

int main() {
    readGraph();
    BFS(S);
    printDistances();
    return 0;
}