Submission #391445

#	Time	Username	Problem	Language	Result	Execution time	Memory
391445		qwerasdfzxcl	Mergers (JOI19_mergers)	C++14	0 / 100	96 ms	41116 KiB

mergers

#include <bits/stdc++.h>

typedef long long ll;
using namespace std;
vector<int> adj[500500], joi[500500];
int col[500500], cnt[500500], lct[500500], val=0, val2=0;
bool visited[500500], visited2[500500], chk[500500];
struct LCA{
    int spa[500500][21], dep[500500];
    void dfs(int s, int pa=0){
        spa[s][0]=pa;
        for (int i=1;i<21 && spa[s][i-1];i++) spa[s][i] = spa[spa[s][i-1]][i-1];
        dep[s] = dep[pa]+1;
        for (auto &v:adj[s]) if (v!=pa){
            dfs(v, s);
        }
    }
    int query(int v, int u){
        if (dep[v]>dep[u]) swap(v, u);
        for (int i=20;i>=0;i--) if (spa[u][i] && dep[spa[u][i]]>dep[v]) u = spa[u][i];
        if (dep[v]!=dep[u]) u = spa[u][0];
        if (v!=u){
            for (int i=20;i>=0;i--) if (spa[v][i] && spa[v][i]!=spa[u][i]) v = spa[v][i], u = spa[u][i];
            v = spa[v][0], u = spa[u][0];
        }
        return v;
    }
}lca;

pair<int, int> dfs1(int s){
    pair<int, int> ret;
    ret.second = 1;
    if (lct[col[s]]==s) ret.first = cnt[col[s]];
    visited[s]=1;
    //printf("%d %d %d\n", s, ret.first, ret.second);
    //printf(" %d %d %d\n", col[s], lct[col[s]], cnt[s]);
    for (auto &v:adj[s]) if (!visited[v]){
        auto tmp = dfs1(v);
        ret.first += tmp.first;
        ret.second += tmp.second;
    }
    if (ret.first==ret.second) chk[s]=1;
    return ret;
}

int dfs2(int s, bool test){
    int ret=0;
    if (chk[s]) ret++;
    if (chk[s] && s!=1 && !test) test=1, val2++;
    visited2[s] = 1;
    for (auto &v:adj[s]) if (!visited2[v]){
        ret += dfs2(v, test);
    }
    if (chk[s] && ret==1 && s!=1) val++;
    return ret;
}

int main(){
    int n, k;
    scanf("%d %d", &n, &k);
    for (int i=0;i<n-1;i++){
        int a, b;
        scanf("%d %d", &a, &b);
        adj[a].push_back(b);
        adj[b].push_back(a);
    }
    for (int i=1;i<=n;i++){
        scanf("%d", col+i);
        cnt[col[i]]++;
        joi[col[i]].push_back(i);
    }
    lca.dfs(1);
    for (int i=1;i<=k;i++){
        if (cnt[i]==1){
            lct[i] = joi[i][0]; continue;
        }
        lct[i] = joi[i][0];
        for (int j=1;j<cnt[i];j++){
            lct[i] = lca.query(lct[i], joi[i][j]);
        }
    }
    dfs1(1);
    dfs2(1, 0);
    /*for (int i=1;i<=k;i++) printf("%d ", lct[i]);
    printf("\n");
    for (int i=1;i<=n;i++) printf("%d ", chk[i]);
    printf("\n");*/
    if (val2==1) val++;
    //printf("%d\n", val2);
    printf("%d\n", (val+1)/2);
    return 0;
}

Compilation message (stderr)

mergers.cpp: In function 'int main()':
mergers.cpp:60:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   60 |     scanf("%d %d", &n, &k);
      |     ~~~~~^~~~~~~~~~~~~~~~~
mergers.cpp:63:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   63 |         scanf("%d %d", &a, &b);
      |         ~~~~~^~~~~~~~~~~~~~~~~
mergers.cpp:68:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   68 |         scanf("%d", col+i);
      |         ~~~~~^~~~~~~~~~~~~

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