제출 #1299039

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1299039		quan606303	Power Plant (JOI20_power)	C++20	0 / 100	2 ms	836 KiB

power

/*
 * @Author: RMQuan 
 * @Date: 2025-12-04 14:00:03 
 * @Last Modified by: RMQuan
 * @Last Modified time: 2025-12-04 16:46:09
 */
/*idea : 



*/
#include <bits/stdc++.h>
bool M1;
#define int long long
#define ll long long
#define INTMAX INT_MAX
#define INTMIN INT_MIN
#define LONGMAX LLONG_MAX
#define LONGMIN LLONG_MIN
#define fi first
#define se second
#define memfull(a,b) memset(a,b,sizeof(a));
#define endl '\n'
#define TASK "TEST"
#define file() if (fopen(TASK".inp","r")){freopen(TASK".inp","r",stdin); freopen(TASK".out","w",stdout);}
using namespace std;
const int MOD=1e9+7;
const int maxn=2e5+7;
vector<int> adj[maxn];
bool is_spl[maxn];
int n,dp[maxn][3];
/*
    dp[u][0]: co it nhat 0 thang spl thang hang
    dp[u][1]: co it nhat 1 thang spl thang hang
    dp[u][2]: co it nhat 2 thang spl thang hang
*/
int ans=0;
void dfs(int u,int p)
{
    if (is_spl[u])
    {
        int cnt1=-1;
        dp[u][1]=1;
        int dem=0;
        int cnt=0;
        for (auto v:adj[u])
        {
            if (v==p)continue;
            dfs(v,u);
            //case 1 : tu keo len
            dp[u][2]=max(dp[u][2],dp[v][1]+1);
            dp[u][2]=max(dp[u][2],dp[v][2]-2);
            cnt+=max(0ll,dp[v][1]);
           // dp[u][1]=max(dp[u][1],dp[v][1]);
           // dp[u][2]=max(dp[u][2],dp[v][2]);
            //case 2 : merge 2 cay lai voi nhau
            cnt1+=max(0ll,max(dp[v][1],dp[v][2]-2));
            dem++;
        }
        if (dem>=2)dp[u][1]=max(dp[u][1],cnt1);
        dp[u][2]=max(dp[u][2],cnt);
    }
    else
    {
        int cnt=0,dem=0;
        for (auto v:adj[u])
        {
            if (v==p)continue;
            dfs(v,u);
            //case 1 : tu keo len
            dp[u][1]=max(dp[u][1],dp[v][1]);
            dp[u][2]=max(dp[u][2],dp[v][2]);
            //case 2 : merge 2 cay lai voi nhau
            cnt+=max(0ll,max(dp[v][1],dp[v][2]-2));
            dem++;
        }
        dp[u][1]=max(dp[u][1],cnt);
        //if (u==3)cerr<<cnt<<endl;
    }
    ans=max({ans,dp[u][0],dp[u][1],dp[u][2]});
   // cerr<<u<<" "<<dp[u][0]<<" "<<dp[u][1]<<" "<<dp[u][2]<<endl;
}
int32_t main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    file();
    cin>>n;
    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++)
    {
        char x;
        cin>>x;
        if (x=='1') is_spl[i]=1;
        else is_spl[i]=0;
    }
    for (int i=1;i<=n;i++)dp[i][1]=dp[i][2]=-1e9;
    dfs(1,0);
    cout<<ans;
    
    return 0;
}

컴파일 시 표준 에러 (stderr) 메시지

power.cpp: In function 'int32_t main()':
power.cpp:25:50: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   25 | #define file() if (fopen(TASK".inp","r")){freopen(TASK".inp","r",stdin); freopen(TASK".out","w",stdout);}
      |                                           ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
power.cpp:88:5: note: in expansion of macro 'file'
   88 |     file();
      |     ^~~~
power.cpp:25:81: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   25 | #define file() if (fopen(TASK".inp","r")){freopen(TASK".inp","r",stdin); freopen(TASK".out","w",stdout);}
      |                                                                          ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
power.cpp:88:5: note: in expansion of macro 'file'
   88 |     file();
      |     ^~~~

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