Submission #253219

#	Time	Username	Problem	Language	Result	Execution time	Memory
253219		egekabas	Capital City (JOI20_capital_city)	C++14	0 / 100	620 ms	66936 KiB

capital_city

#include <bits/stdc++.h>
#define ff first
#define ss second
#define pb push_back
#define mp make_pair
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<ll, ll> pll;
typedef pair<ull, ull> pull;
typedef pair<int, int> pii;
typedef pair<ld, ld> pld;
int n, k;
vector<int> g[200009];
int col[200009];
int depth[200009];
int dad[200009][30];
void dfs1(int v, int prt){
    for(int i = 1; i < 30; ++i)
        dad[v][i] = dad[dad[v][i-1]][i-1];
    for(auto u : g[v])
        if(u != prt){
            depth[u] = depth[v]+1;
            dad[u][0] = v;
            dfs1(u, v);
        }
}
int lca(int x, int y){
    if(depth[x] < depth[y])
        swap(x, y);
    for(int i = 29; i >= 0; --i)
        if(depth[dad[x][i]] >= depth[y])
            x = dad[x][i];
    if(x == y) return x;
    for(int i = 29; i >= 0; --i)
        if(dad[x][i] != dad[y][i]){
            x = dad[x][i];
            y = dad[y][i];
        }
    return dad[x][0];
}
int root[200009];
int prt[200009];
int sz[200009];
set<int> con[200009];
int find(int x){
    if(prt[x] == x) return x;
    return prt[x] = find(prt[x]);
}
void merge(int x, int y){
    x = find(x);
    y = find(y);
    if(x == y) return;
    if(con[y].size() > con[x].size())
        swap(x, y);
    con[y].erase(x);
    con[x].erase(y);
    for(auto u : con[y])
        con[x].insert(u);
    root[x] = min(root[x], root[y]);
    prt[y] = x;
    sz[x] += sz[y];
}
void dfs2(int v, int prt){
    for(auto u : g[v])
        if(u != prt){
            dfs2(u, v);
            if(col[u] != col[v] && depth[u] != root[col[u]]){
                con[col[u]].insert(col[v]);
                if(con[col[v]].find(col[u]) != con[col[v]].end()){
                    merge(col[u], col[v]);
                    col[v] = find(col[v]);
                }
            }
        }
}
int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    
    //freopen("in.txt", "r", stdin);
    //freopen("out.txt", "w", stdout);
    
    cin >> n >> k;
    for(int i = 0; i < n-1; ++i){
        int x, y;
        cin >> x >> y;
        g[x].pb(y);
        g[y].pb(x);
    }
    for(int i = 1; i <= n; ++i)
        cin >> col[i];
    
    depth[1] = 1;
    dfs1(1, 0);
    for(int i = 1; i <= n; ++i){
        if(root[col[i]] == 0)
            root[col[i]] = i;
        else
            root[col[i]] = lca(root[col[i]], i);
    }
    for(int i = 1; i <= k; ++i){
        root[i] = depth[root[i]];
        prt[i] = i;
        sz[i] = 1;
    }
    dfs2(1, 0);
    int ans = 1e9;
    for(int i = 1; i <= k; ++i){
        int x = find(i);
        if(con[x].empty())
            ans = min(ans, sz[x]);
    }
    cout << ans-1 << '\n';
}

• Subtask 1: 0 / 1
• Subtask 2: 0 / 10
• Subtask 3: 0 / 30
• Subtask 4: 0 / 59