Submission #1241228

#	Time	Username	Problem	Language	Result	Execution time	Memory
1241228		knhatdev	Mousetrap (CEOI17_mousetrap)	C++20	0 / 100	220 ms	125688 KiB

mousetrap

#include<bits/stdc++.h>
#define int long long
#define ii pair<int,int>
#define fi first
#define se second
#define task ""
using namespace std;

const int N = 1e6 + 5, mod = 1e9 + 7;
int n, a[N], dp[N], par[N], ans, t, m;
vector<ii> vec[N];
vector<int> g[N];

void dfs(int u, int p = -1)
{
    dp[u] = 1;
    for(int v : g[u])
    {
        if(v == p) continue;
        dfs(v, u);
        par[v] = u;
        dp[u] = max(dp[u], dp[v] + 1);
        vec[u].push_back(ii(dp[v], v));
    }
    sort(vec[u].begin(), vec[u].end(), [](ii x, ii y)
    {
        return x.fi > y.fi;
    });
}

void dfs2(int u)
{
    ans++;
    if(vec[u].size() <= 1)
    {
        ans++;
        return;
    }
    ans += vec[u].size() - 1;
    dfs2(vec[u][1].se);
}
main(){
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    if(fopen(task ".inp", "r")){
        freopen(task ".inp", "r", stdin);
        freopen(task ".out", "w", stdout);
    }
    cin >> n >> t >> m;
    for(int i = 1; i < n; i++)
    {
        int u, v; cin >> u >> v;
        g[u].push_back(v);
        g[v].push_back(u);
    }
    dfs(t);
    dfs2(m);
    ans--;
    int tmp = par[m];
    while(tmp != t)
    {
        ans += vec[tmp].size() - 1;
        tmp = par[tmp];
    }
    cout << ans;
}

Compilation message (stderr)

mousetrap.cpp:42:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   42 | main(){
      | ^~~~
mousetrap.cpp: In function 'int main()':
mousetrap.cpp:45:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   45 |         freopen(task ".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
mousetrap.cpp:46:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   46 |         freopen(task ".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 20
• Subtask 2: 0 / 25
• Subtask 3: 0 / 20
• Subtask 4: 0 / 35