UVa - 10959 - The Party, Part I

#include <iostream>
#include <cstdio>
#include <cstring>
#include <vector>
#include <queue>
#include <algorithm>
#define L 1003
using namespace std;

int P, D;
vector <int> node[L];
int check1[L][L];
int visited[L][L], ans[L];

void BFS(){
    queue <int> tracking;
    tracking.push(0);
    ans[0] = 0;
    int Z;
    while(!tracking.empty()){
        int u = tracking.front();
        int sz = node[u].size();
        for(int i = 0; i < sz; i++){
            int v = node[u][i];
            if(!visited[u][v] && !visited[v][u]){
                visited[u][v] = 1, visited[v][u] = 1;
                tracking.push(v);
                if(ans[v] == -1)ans[v] = ans[u]+1;
            }
        }
        tracking.pop();
    }
}

int main(){
    int t, x, y;
    cin >> t;
    while(t--){
        memset(check1, 0, sizeof(check1));
        memset(visited, 0, sizeof(visited));
        memset(ans, -1, sizeof(ans));
        cin >> P >> D;
        for(int i = 1; i <= D; i++){
            cin >> x >> y;
            if(check1[x][y] || check1[y][x])continue;
            check1[x][y] = 1, check1[y][x] = 1;
            node[x].push_back(y);
            node[y].push_back(x);
        }
        BFS();
        for(int i = 1; i < P; i++)cout << ans[i] << endl;
        if(t)cout << endl;
        for(int i = 0; i < L; i++)node[i].clear();
    }
    return 0;
}