Submission #355256

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
355256	2021-01-22T10:51:02 Z	blue	Computer Network (BOI14_network)	C++11	Compilation error	0 ms	0 KB

network

#include <iostream>
#include <queue>
using namespace std;

int n;
vector<int> edge[500001];
vector<int> edge_size(500001, 0);
vector<int> p(500001, 0);
vector<int> dfs_leaf;

void dfs(int u)
{
    if(edge[u].size() == 1) dfs_leaf.push_back(u);
    for(int v: edge[u])
    {
        if(p[u] == v) continue;
        dfs(v);
    }
}

int main()
{
    cin >> n;
    int a, b;
    for(int i = 1; i <= n-1; i++)
    {
        cin >> a >> b;
        edge[a].push_back(b);
        edge_size[a]++;
        edge[b].push_back(a);
        edge_size[b]++;
    }

    queue<int> tbv;
    for(int i = 1; i <= n; i++) if(edge_size[i] == 1) tbv.push(i);
    while(!tbv.empty())
    {
        a = tbv.front();
        tbv.pop();

        for(int v: edge[a])
        {
            if(p[v] == a) continue;
            p[a] = v;
            edge_size[v]--;
            if(edge_size[v] == 1) tbv.push(v);
        }
    }

    int root = a;
    dfs(root);

    int s = dfs_leaf.size();

    if(s % 2 == 0)
    {
        cout << s/2 << '\n';
        for(int i = 0; i < s/2; i++) cout << dfs_leaf[i] << ' ' << dfs_leaf[s/2 + i] << '\n';
    }
    else
    {
        s--;
        cout << s/2 + 1 << '\n';
        for(int i = 0; i < s/2; i++) cout << dfs_leaf[i] << ' ' << dfs_leaf[s/2 + i] << '\n';
        cout << dfs_leaf[0] << ' ' << dfs_leaf[s] << '\n';
    }
}

Compilation message

grader.c: In function 'int main()':
grader.c:48:11: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   48 |     scanf ("%d%d%d%d", &N, &a, &b, &M);
      |     ~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
grader.c:51:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   51 |             scanf("%d", &distance[u][v]);
      |             ~~~~~^~~~~~~~~~~~~~~~~~~~~~~
/tmp/cccxce8t.o: In function `main':
grader.c:(.text.startup+0x0): multiple definition of `main'
/tmp/ccEj901j.o:network.cpp:(.text.startup+0x0): first defined here
/tmp/cccxce8t.o: In function `main':
grader.c:(.text.startup+0xc5): undefined reference to `findRoute(int, int, int)'
collect2: error: ld returned 1 exit status