Submission #1020388

#	Time	Username	Problem	Language	Result	Execution time	Memory
1020388		Thanhs	Untitled (POI11_rot)	C++17	100 / 100	197 ms	65536 KiB

Main

#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
// #define int long long
// #define double long double
#define pb push_back
 
#define endl '\n'
#define fastIO ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);
#define setmin(x,y) x=min((x),(y))
#define setmax(x,y) x=max((x),(y))
#define sqr(x) (x)*(x)
#define fi first
#define se second
 
mt19937 hdp(chrono::high_resolution_clock::now().time_since_epoch().count());
int rand(int l,int r){return l+((hdp()%(r-l+1))+r-l+1)%(r-l+1);}
 
const int N = 4e5 + 5;
const int mod = 998244353;
const int SQ = 450;
const int inf = 1e9;
const int bound = 1e7;
 
vector<int> g[N];
int n,m,c[N],sz[N],par[N];
vector<int> V[N];
stack<int> st;
long long dp[N];
 
int bit[N];
void upd(int i)
{
    for(;i<=n;i+=i&-i) 
    {
        st.push(i);
        bit[i]++;
    }
}
int get(int i)
{
    int res=0;
    for(;i;i-=i&-i) res+=bit[i];
    return res;
}
 
void dfs(int u=1,int p=0,bool keep=0)
{
    int bc=0;
    for(int v:g[u]) if(v!=p&&sz[v]>sz[bc]) bc=v;
    for(int v:g[u]) if(v!=p&&v!=bc) dfs(v,u,0);
    if(bc)
    {
        dfs(bc,u,1);
        swap(V[u],V[bc]);
        dp[u]=dp[bc];
    }
    for(int v:g[u]) if(v!=p&&v!=bc) dp[u]+=dp[v];
    long long sum1=0,sum2=0,xx=V[u].size();
    for(int v:g[u]) if(v!=bc) for(auto t:V[v])
    {
        V[u].pb(t);
        int x=get(t);
        sum1+=x;
        sum2+=xx-x;
    }
    dp[u]+=min(sum1,sum2);
    for(int v:g[u]) if(v!=bc) for(auto t:V[v]) upd(t);
    if(c[u])
    {
        V[u].pb(c[u]);
        upd(c[u]);
    }
    if(!keep) 
    {
        while(!st.empty())
        {
            bit[st.top()]=0;
            st.pop();
        }
    }
}
 
void dfs_sz(int u=1,int p=0)
{
    sz[u]=1;
    for(auto v:g[u]) if(v!=p)
    {
        dfs_sz(v,u);
        sz[u]+=sz[v];
    }
}
 
signed main()
{
    if (fopen("in.txt", "r")) {
        freopen("in.txt","r",stdin);
        freopen("out.txt","w",stdout);
    }
    fastIO
    cin>>n;
    int u=0,v=0;
    for(int m=1;m<2*n;m++)
    {
        cin>>c[m];
        g[u].pb(m);
        par[m]=u;
        if(c[m]) 
        {
            while(g[u].size()==2) u=par[u];
        }
        else u=m;
    }
    dfs_sz();
    dfs();
    cout<<dp[1];
}

Compilation message (stderr)

rot.cpp: In function 'int main()':
rot.cpp:103:13: warning: unused variable 'v' [-Wunused-variable]
  103 |     int u=0,v=0;
      |             ^
rot.cpp:98:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   98 |         freopen("in.txt","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~
rot.cpp:99:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   99 |         freopen("out.txt","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 9 / 9
• Subtask 2: 9 / 9
• Subtask 3: 9 / 9
• Subtask 4: 9 / 9
• Subtask 5: 9 / 9
• Subtask 6: 9 / 9
• Subtask 7: 9 / 9
• Subtask 8: 9 / 9
• Subtask 9: 9 / 9
• Subtask 10: 9 / 9
• Subtask 11: 10 / 10