Submission #567854

#	Time	Username	Problem	Language	Result	Execution time	Memory
567854		stevancv	Mergers (JOI19_mergers)	C++14	0 / 100	84 ms	32040 KiB

mergers

#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define sp ' '
#define en '\n'
#define smin(a, b) a = min(a, b)
#define smax(a, b) a = max(a, b)
using namespace std;
const int N = 5e5 + 2;
const int M = 5e5 + 2;
int mod = 1000000007;
vector<int> g[N];
int lift[N][19], in[N], out[N], tsz;
void Dfs(int s, int e) {
    in[s] = ++tsz;
    lift[s][0] = e;
    for (int i = 1; i < 19; i++) lift[s][i] = lift[lift[s][i - 1]][i - 1];
    for (int u : g[s]) {
        if (u != e) {
            Dfs(u, s);
        }
    }
    out[s] = tsz;
}
bool Ancestor(int a, int b) {
    return in[a] <= in[b] && out[b] <= out[a];
}
int Lca(int a, int b) {
    if (Ancestor(a, b)) return a;
    if (Ancestor(b, a)) return b;
    for (int i = 18; i >= 0; i--) {
        if (lift[a][i] != -1 && !Ancestor(lift[a][i], b)) a = lift[a][i];
    }
    return lift[a][0];
}
int sum[N], sz[N], ok[N], nz[N];
void Dfs1(int s, int e) {
    sz[s] = 1;
    for (int u : g[s]) {
        if (u != e) {
            Dfs1(u, s);
            sz[s] += sz[u];
            sum[s] += sum[u];
        }
    }
    ok[s] = sum[s] == sz[s];
}
int dp[N][3];
int F(int s) {
    return (dp[s][1] + 1) / 2 + dp[s][2];
}
void Dfs2(int s, int e) {
    dp[s][0] = ok[s];
    bool f = 1;
    for (int u : g[s]) {
        if (u != e) {
            Dfs2(u, s);
            dp[s][0] += dp[u][0];
            if (F(u) <= dp[u][0]) {
                f = 0;
                dp[s][1] += dp[u][1];
                dp[s][2] += dp[u][2];
            }
            else dp[s][1] += dp[u][0];
        }
    }
    if (nz[s] != nz[0]) dp[s][2] += f;
}
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int n, k;
    cin >> n >> k;
    for (int i = 0; i < n - 1; i++) {
        int a, b;
        cin >> a >> b;
        g[a - 1].push_back(b - 1);
        g[b - 1].push_back(a - 1);
    }
    Dfs(0, -1);
    vector<vector<int>> pos(k);
    for (int i = 0; i < n; i++) {
        cin >> nz[i];
        nz[i] -= 1;
        pos[nz[i]].push_back(i);
    }
    for (int i = 0; i < k; i++) {
        if (pos[i].empty()) continue;
        int tr = pos[i][0];
        for (int j = 0; j < pos[i].size(); j++) {
            tr = Lca(tr, pos[i][j]);
        }
        sum[tr] += pos[i].size();
    }
    Dfs1(0, -1);
    Dfs2(0, -1);
    int x, y;
    x = y = 0;
    for (int j : g[0]) {
        int u = (x + dp[j][0] + 1) / 2 + y;
        int v = (x + dp[j][1] + 1) / 2 + y + dp[j][2];
        if (u < v) {
            x += dp[j][0];
        }
        else {
            x += dp[j][1];
            y += dp[j][2];
        }
    }
    cout << (x + 1) / 2 + y << en;
    return 0;
}

Compilation message (stderr)

mergers.cpp: In function 'int main()':
mergers.cpp:91:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   91 |         for (int j = 0; j < pos[i].size(); j++) {
      |                         ~~^~~~~~~~~~~~~~~

• Subtask 1: 0 / 10
• Subtask 2: 0 / 24
• Subtask 3: 0 / 14
• Subtask 4: 0 / 22
• Subtask 5: 0 / 30