제출 #386439

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
386439		nafis_shifat	Mergers (JOI19_mergers)	C++14	100 / 100	1509 ms	154732 KiB

mergers

#include<bits/stdc++.h>
#define ll long long
#define pii pair<int,int>
using namespace std;
const int mxn=5e5+5;
const int inf=1e9;
vector<int> v;
vector<int> adj[mxn];

int S[mxn];
vector<int> con[mxn];
int level[mxn];
int dp[mxn][20];

struct DSU {
    int parent[mxn];
    void init() {
        for(int i = 1; i < mxn; i++) parent[i] = i;
    }
    int findrep(int u) {
        return parent[u] == u ? u : parent[u] = findrep(parent[u]);
    }
    void unite(int u,int v) {
        u = findrep(u);
        v = findrep(v);
        if(u == v) return;
        if(level[u] < level[v]) swap(u,v);
        parent[u] = v;
    }

} dsu1,dsu2;


bool dfs(int cur,int prev,int src) {
    if(cur == src) return true;


    bool f = false;

    for(int u : adj[cur]) {
        if(u == prev) continue;
        f |= dfs(u,cur,src);
    }
    if(f) v.push_back(cur);
    return f;
}

void DFS(int cur,int prev) {
    level[cur] = level[prev] + 1;
    dp[cur][0] = prev;
    for(int i = 1; i < 20; i++) dp[cur][i] = dp[dp[cur][i - 1]][i - 1];
    for(int u : adj[cur]) {
        if(u != prev) {
            DFS(u,cur);
            if(S[u] == S[cur]) dsu1.unite(u,cur);
        }
    }
}

int findLCA(int u,int v){
    if(level[u] < level[v])swap(u,v);
    int diff = level[u] - level[v];
    for(int i = 0; i < 20; i++) if((diff>>i) & 1) u = dp[u][i];
    if(u == v) return u;
    for(int i = 19; i >= 0; i--) {
        if(dp[u][i] != dp[v][i]) {
            u = dp[u][i];
            v = dp[v][i];
        }
    }
    return dp[u][0];
}

void process(int u,int lv) {
    int cu = dsu1.findrep(u);
    int clv = level[cu];
    while(clv > lv) {
        int ccu = dsu1.findrep(dp[cu][0]);
        dsu1.unite(cu,ccu);
        dsu2.unite(S[cu],S[ccu]);
        cu = ccu;
        clv = level[cu];
    }
}


int main() {
    int n,k;
    cin >> n >> k;

    for(int i = 1; i < n; i++) {
        int u,v;
        cin >> u >> v;

        adj[u].push_back(v);
        adj[v].push_back(u);

    }

    for(int i = 1; i <= n; i++) {
        cin >> S[i];
        con[S[i]].push_back(i);
    }

    DFS(1,0);

    dsu1.init();
    dsu2.init();

    for(int i = 1; i <= k; i++) {
        sort(con[i].begin(),con[i].end(),[](int a,int b) {
            return level[a] < level[b];
        });
        for(int j = 1; j < con[i].size(); j++) {
            v.clear();
            int u = con[i][j];
            int v = con[i][j - 1];
            int lca = findLCA(u,v);

            process(u,level[lca]);
            process(v,level[lca]);
        }
    }
    int deg[k + 1] = {};

    for(int i = 1; i <= n; i++) {
        int x = dsu2.findrep(S[i]);
        for(int u : adj[i]) {
            if(x == dsu2.findrep(S[u])) continue;
            deg[dsu2.findrep(S[u])]++;
        }
    }

    int leaf = 0;
    for(int i = 1; i <= k; i++) {
        if(dsu2.parent[i] == i && deg[i] == 1) leaf++;
    }
    cout<<(leaf + 1) / 2<<endl;




}

컴파일 시 표준 에러 (stderr) 메시지

mergers.cpp: In function 'int main()':
mergers.cpp:114:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  114 |         for(int j = 1; j < con[i].size(); j++) {
      |                        ~~^~~~~~~~~~~~~~~

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