Submission #375899

#	Time	Username	Problem	Language	Result	Execution time	Memory
375899		topovik	Papričice (COCI20_papricice)	C++14	110 / 110	345 ms	21740 KiB

papricice

#include <bits/stdc++.h>
#define f first
#define s second
#define pb push_back
#define len(x) x.size()
#define debug(x) cout << #x << " is " << x << endl

using namespace std;

typedef long long ll;
typedef long double ld;

const ll N = 1e6 + 100;
const ll oo = 1e9 + 7;

set <int> anc;
set <int> not_anc;
set<int> :: iterator mn, mx;

vector <vector <int> > a;

int sz[N];
int n;
int ans = oo;

int calc_sz(int x, int y)
{
    sz[x] = 1;
    for (int i = 0; i < len(a[x]); i++)
        if (a[x][i] != y) sz[x] += calc_sz(a[x][i], x);
    return sz[x];
}

void update(int x, int y, int z)
{
    ans = min(ans, max(max(x, y), z) - min(min(x, y), z));
}

void Check(int x)
{
    if (!anc.empty())
    {
        mn = anc.lower_bound((n + sz[x]) / 2);
        if (mn != anc.end()) update(sz[x], *mn - sz[x], n - *mn);
        if (mn != anc.begin())
        {
            mn--;
            update(sz[x], *mn - sz[x], n - *mn);
        }
    }
    if (!not_anc.empty())
    {
        mn = not_anc.lower_bound((n - sz[x]) / 2);
        mx = not_anc.end();
        if (mn != not_anc.begin() && !not_anc.empty()) {mx = --mn; mn++;}
        if (mn != not_anc.end()) update(sz[x], *mn, n - sz[x] - *mn);
        if (mx != not_anc.end()) update(sz[x], *mx, n - sz[x] - *mx);
    }
}

void Rec(int x, int y)
{
    Check(x);
    anc.insert(sz[x]);
    for (int i = 0; i < len(a[x]); i++)
        if (a[x][i] != y) Rec(a[x][i], x);
    not_anc.insert(sz[x]);
    anc.erase(sz[x]);
}

int main()
{
    cin >> n;
    a.resize(n);
    for (int i = 0; i < n - 1; i++)
    {
        int x, y;
        cin >> x >> y;
        a[--x].pb(--y);
        a[y].pb(x);
    }
    calc_sz(0, 0);
    Rec(0, 0);
    cout << ans;
}

Compilation message (stderr)

papricice.cpp: In function 'int calc_sz(int, int)':
papricice.cpp:29:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   29 |     for (int i = 0; i < len(a[x]); i++)
      |                       ^
papricice.cpp: In function 'void Rec(int, int)':
papricice.cpp:65:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   65 |     for (int i = 0; i < len(a[x]); i++)
      |                       ^

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