Submission #1222121

#	Time	Username	Problem	Language	Result	Execution time	Memory
1222121		huudai	Papričice (COCI20_papricice)	C++20	110 / 110	173 ms	39872 KiB

papricice

#include <bits/stdc++.h>

using namespace std;

#define int long long
#define ll long long
#define fi first
#define se second
#define pii pair<int, int>
#define pll pair<ll,ll>
#define mp make_pair
#define pb push_back

#define BIT(x,i) (((x)>>(i))&1)
#define MASK(i) (1LL<<(i))  

template<typename T1, typename T2> bool minimize(T1 &a, T2 b)
    {if(a>b) a=b; else return 0; return 1;}
template<typename T1, typename T2> bool maximize(T1 &a, T2 b)
    {if(a<b) a=b; else return 0; return 1;}

#define file "task"

const int maxn = 2e5 + 5;
const int MOD  = 1e9 + 7;
const int oo   = 1e9;
const ll  OO   = 1e18;

int n;
int sz[maxn];
int ans = oo;
vector<int> g[maxn];
set<int> ancestor;
set<int> s[maxn];

int max(int a, int b, int c){
    return max(max(a, b), c);
}
int min(int a, int b, int c){
    return min(min(a, b), c);
}

void input(){
    cin >> n;
    for(int i = 1; i <= n - 1; i++){
        int u, v; cin >> u >> v;
        g[u].pb(v);
        g[v].pb(u);
    }
}

void prep(int u, int dad){
    sz[u] = 1;
    for(int v : g[u]){
        if(v == dad) continue;
        prep(v, u);
        sz[u] += sz[v];
    }    
}

void get(set<int> &s, int w){
    int sum = n - w;
    auto it = s.lower_bound(sum / 2);
    if(it != s.end()){
        minimize(ans, max(w, (*it), sum - (*it)) - min(w, (*it), sum - (*it)));
    }
    if(it != s.begin()){
        it--;
        minimize(ans, max(w, (*it), sum - (*it)) - min(w, (*it), sum - (*it)));
    }
}
void dfs(int v, int dad){
    for(int u : g[v]){
        if(u == dad) continue;
        dfs(u, v);
        //dsu on tree
        if(s[u].size() > s[v].size()) swap(s[u], s[v]);

        for(int w : s[u]){
            get(s[v], w);
        }
        for(int w : s[u]){
            s[v].insert(w);
        }
    }

    get(s[v], n - sz[v]);
    s[v].insert(sz[v]);
}

void proc(){
    ans = oo;
    prep(1, 1);
    dfs(1, 1);

    cout << ans;
}

signed main(){
    cin.tie(nullptr)->sync_with_stdio(0); cout.tie(nullptr);    
    if(fopen(file".inp", "r")){
        freopen(file".inp", "r", stdin);
        freopen(file".out", "w", stdout);
    }
    
    input();
    proc();

    return 0;
}

Compilation message (stderr)

papricice.cpp: In function 'int main()':
papricice.cpp:102:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  102 |         freopen(file".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
papricice.cpp:103:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  103 |         freopen(file".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 15 / 15
• Subtask 2: 35 / 35
• Subtask 3: 60 / 60