Submission #862042

#	Time	Username	Problem	Language	Result	Execution time	Memory
862042		NeroZein	Network (BOI15_net)	C++17	0 / 100	3 ms	12124 KiB

net

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <limits.h>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <algorithm>
#include <string>
#include <functional>
#include <vector>
#include <numeric>
#include <deque>
#include <bitset>
#include <iostream>
using namespace std;
typedef long long lint;
typedef long double llf;
typedef pair<int, int> pi;

int n;
vector<int> graph[500005];
vector<int> v;

void dfs(int x, int p){
  int cnt = 0;
  for(auto &i : graph[x]){
    if(i == p) continue;
    dfs(i, x);
    cnt++;
  }
  if(cnt == 0) v.push_back(x);
}

int main(){
  scanf("%d",&n);
  for(int i=0; i<n-1; i++){
    int s, e;
    scanf("%d %d",&s,&e);
    graph[s].push_back(e);
    graph[e].push_back(s);
  }
  for(int i=1; i<=n; i++){
    if(graph[i].size() != 1){
      dfs(i, 0);
      break;
    }
  }
  printf("%d\n",(v.size() + 1) / 2);
  for(int i = 1; i < v.size(); i += 2){
    printf("%d %d\n",v[i], v[i - 1]);
  }
  if (v.size() & 1) {
    cout << v[0] << ' ' << v.back() << '\n'; 
  }
}

Compilation message (stderr)

net.cpp: In function 'int main()':
net.cpp:51:12: warning: format '%d' expects argument of type 'int', but argument 2 has type 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wformat=]
   51 |   printf("%d\n",(v.size() + 1) / 2);
      |           ~^    ~~~~~~~~~~~~~~~~~~
      |            |                   |
      |            int                 std::vector<int>::size_type {aka long unsigned int}
      |           %ld
net.cpp:52:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   52 |   for(int i = 1; i < v.size(); i += 2){
      |                  ~~^~~~~~~~~~
net.cpp:38:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   38 |   scanf("%d",&n);
      |   ~~~~~^~~~~~~~~
net.cpp:41:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   41 |     scanf("%d %d",&s,&e);
      |     ~~~~~^~~~~~~~~~~~~~~

• Subtask 1: 0 / 18
• Subtask 2: 0 / 45
• Subtask 3: 0 / 37