Submission #253652

#	Time	Username	Problem	Language	Result	Execution time	Memory
253652		IgorI	Cats or Dogs (JOI18_catdog)	C++17	38 / 100	3063 ms	13544 KiB

catdog

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

const int INF = 1e9;
const int N = 100002;

ll n;
vector<int> graph[N];
ll x[N];
ll papa[N];
ll dp[N][2];

void dfs(int v, int p)
{
    papa[v] = p;
    for (auto u : graph[v]) if (u != p)
    {
        dfs(u, v);
    }
}

int answer()
{
    return min(dp[0][0], dp[0][1]);
}

void initialize(int n0, vector<int> a, vector<int> b)
{
    n = n0;
    for (int i = 0; i < n - 1; i++)
    {
        a[i]--, b[i]--;
        graph[a[i]].push_back(b[i]);
        graph[b[i]].push_back(a[i]);
    }
    for (int i = 0; i < n; i++)
    {
        x[i] = -1;
    }
    dfs(0, 0);
}

int cat(int v)
{
    v--;
    x[v] = 0;
    pair<int, int> pdp = {dp[v][0], dp[v][1]};
    dp[v][1] = INF;
    while (papa[v] != v)
    {
        pair<int, int> sdp = {dp[papa[v]][0], dp[papa[v]][1]};
        dp[papa[v]][0] -= min(pdp.first, pdp.second + 1);
        dp[papa[v]][1] -= min(pdp.first + 1, pdp.second);
        dp[papa[v]][0] += min(dp[v][0], dp[v][1] + 1);
        dp[papa[v]][1] += min(dp[v][0] + 1, dp[v][1]);
        pdp = sdp;
        v = papa[v];
    }
    return answer();
}

int dog(int v)
{
    v--;
    x[v] = 1;
    pair<int, int> pdp = {dp[v][0], dp[v][1]};
    dp[v][0] = INF;
    while (papa[v] != v)
    {
        pair<int, int> sdp = {dp[papa[v]][0], dp[papa[v]][1]};
        dp[papa[v]][0] -= min(pdp.first, pdp.second + 1);
        dp[papa[v]][1] -= min(pdp.first + 1, pdp.second);
        dp[papa[v]][0] += min(dp[v][0], dp[v][1] + 1);
        dp[papa[v]][1] += min(dp[v][0] + 1, dp[v][1]);
        pdp = sdp;
        v = papa[v];
    }
    return answer();
}

int neighbor(int v)
{
    v--;
    x[v] = -1;
    pair<int, int> pdp = {dp[v][0], dp[v][1]};
    dp[v][0] = 0, dp[v][1] = 0;
    for (auto u : graph[v]) if (u != papa[v])
    {
        dp[v][0] += min(dp[u][0], dp[u][1] + 1);
        dp[v][1] += min(dp[u][0] + 1, dp[u][1]);
    }
    while (papa[v] != v)
    {
        pair<int, int> sdp = {dp[papa[v]][0], dp[papa[v]][1]};
        dp[papa[v]][0] -= min(pdp.first, pdp.second + 1);
        dp[papa[v]][1] -= min(pdp.first + 1, pdp.second);
        dp[papa[v]][0] += min(dp[v][0], dp[v][1] + 1);
        dp[papa[v]][1] += min(dp[v][0] + 1, dp[v][1]);
        pdp = sdp;
        v = papa[v];
    }
    return answer();
}

#ifdef LOCAL
int main()
{
    int n;
    cin >> n;
    vector<int> a(n - 1), b(n - 1);
    for (int i = 0; i < n - 1; i++)
    {
        cin >> a[i] >> b[i];
    }
    initialize(n, a, b);
    int q;
    cin >> q;
    while (q--)
    {
        int t, v;
        cin >> t >> v;
        if (t == 1) cout << cat(v) << endl;
        if (t == 2) cout << dog(v) << endl;
        if (t == 3) cout << neighbor(v) << endl;
    }
}
#endif // LOCAL

• Subtask 1: 8 / 8
• Subtask 2: 30 / 30
• Subtask 3: 0 / 62