제출 #846673

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
846673		vjudge1	Torrent (COI16_torrent)	C++17	69 / 100	318 ms	36812 KiB

torrent

#include<bits/stdc++.h>
#define ll long long
#define fi first
#define se second
using namespace std;
const ll nmax=3e5+5;
int n, a, b, dp[nmax], now, ans = 1e9;
vector<int> g[nmax], vt[nmax], res;
bool vis[nmax];
pair<int, int> p;

bool kt(int u, int v)
{
    if(u == p.fi && v == p.se)
        return false;
    if(u == p.se && v == p.fi)
        return false;
    return true;
}

void dis(int u)
{
    vis[u] = true;
    if(u == b)
    {
        dp[b] = 1;
        res.push_back(b);
        return;
    }
    for(auto v: g[u])
    {
        if(!vis[v])
        {
            dis(v);
            dp[u] += dp[v];
        }
    }
    if(dp[u] != 0) res.push_back(u);
}

void dfs(int u)
{
    vt[u].clear();
    dp[u]=1;
    for(auto v:g[u])
    {
        if(dp[v] == 0 && kt(u, v))
        {
            dfs(v);
            vt[u].push_back(dp[v]);
        }
    }
    sort(vt[u].begin(), vt[u].end(), greater<int>());
    for(int i=0; i<vt[u].size(); i++)
        dp[u]=max(dp[u], vt[u][i]+1+i);
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    cin>>n>>a>>b;
    for(int x, y, i=1; i<n; i++)
    {
        cin>>x>>y;
        g[x].push_back(y);
        g[y].push_back(x);
    }
    dis(a);
    int l=0, r=res.size()-2, mid;
    while(l <= r)
    {
        mid = (l+r)/2;
        memset(dp, 0, sizeof(dp));
        p = {res[mid], res[mid+1]};
        dfs(a), dfs(b);
        if(dp[a] > dp[b]) r = mid-1;
        else l = mid+1;
        now = max(dp[a]-1, dp[b]-1);
        ans = min(ans, now);
    }
    cout<<ans;
}

컴파일 시 표준 에러 (stderr) 메시지

torrent.cpp: In function 'void dfs(int)':
torrent.cpp:54:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   54 |     for(int i=0; i<vt[u].size(); i++)
      |                  ~^~~~~~~~~~~~~

• Subtask 1: 0 / 31
• Subtask 2: 69 / 69