Cod sursa(job #2222439)

Utilizator inquisitorAnders inquisitor Data 16 iulie 2018 23:41:31
Problema BFS - Parcurgere in latime Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 2.26 kb
#include <bits/stdc++.h>

#define BUFFER_SIZE 12500000

char buffer[BUFFER_SIZE], *head = buffer, *writeHead = buffer;

bool isDigit[255];

void parseInit()
{
    buffer[fread(buffer, 1, BUFFER_SIZE, stdin)] = 0;

    for(int i = 47; i < 58; ++i) isDigit[i] = 1;
}

__attribute__((always_inline)) int get_int()
{
    int number = 0;

    for(; !isDigit[*head]; ++head);

    for(;  isDigit[*head]; ++head)

        number = number * 10 + (*head) - 48;

    return number;
}

__attribute__((always_inline)) void put_int(int x)
{
    if(x == 0)
    {
        *(writeHead++) = 48; *(writeHead++) = 32;

        return;
    }

    if(x < 0)
    {
        *(writeHead++) = 45; *(writeHead++) = 49; *(writeHead++) = 32;

        return;
    }

    char *old = writeHead;

    while(x)
    {
        *(writeHead++) = x % 10 + 48;

        x /= 10;
    }

    std::reverse(old, writeHead);

    *(writeHead++) = 32;
}

#define MAX_N 100010
#define MAX_M 1000010

int edge[MAX_M];
int degree[MAX_N];
char level[MAX_N];

void BFS(int s)
{
    int q[MAX_N], front = 0, end = 0;

    level[s] = 1;

    q[0] = s;

    while(front <= end)
    {
        int current = q[front];

        for(int it = degree[current], tar = degree[current + 1]; it != tar; ++it)
        {
            int child = edge[it];

            if(level[child] == 0)
            {
                q[++end] = child;

                level[child] = level[current] + 1;
            }
        }

        ++front;
    }
}

int main()
{
    freopen("bfs.in", "r", stdin);
    freopen("bfs.out", "w", stdout);

    parseInit();

    int N = get_int(), M = get_int(), start = get_int();

    for(int i = 0; i < M; ++i)
    {
        ++degree[get_int()];

        get_int();
    }

    for(int i = 1; i <= N; ++i)
    {
        degree[i] += degree[i - 1];
    }

    degree[N + 1] = M;

    head = buffer;

    get_int(), get_int(), get_int();

    for(int i = 0; i < M; ++i)
    {
        int u = get_int(), v = get_int();

        edge[--degree[u]] = v;
    }

    BFS(start);

    for(int i = 1; i <= N; ++i)
    {
        put_int(level[i] - 1);
    }

    fwrite(buffer, 1, writeHead - buffer, stdout);

    return 0;
}