제출 #890054

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
890054		Kutan	구슬과 끈 (APIO14_beads)	C++14	100 / 100	125 ms	22308 KiB

beads

// Cao Quang Hung
#include <cassert>
#include <cctype>
#include <cerrno>
#include <cfloat>
#include <ciso646>
#include <climits>
#include <clocale>
#include <cmath>
#include <csetjmp>
#include <csignal>
#include <cstdarg>
#include <cstddef>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <ccomplex>
#include <cfenv>
#include <cinttypes>
#include <cstdbool>
#include <cstdint>
#include <ctgmath>
#include <cwchar>
#include <cwctype>
#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <locale>
#include <map>
#include <memory>
#include <new>
#include <numeric>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <typeinfo>
#include <utility>
#include <valarray>
#include <vector>
#include <array>
#include <atomic>
#include <chrono>
#include <condition_variable>
#include <forward_list>
#include <future>
#include <initializer_list>
#include <mutex>
#include <random>
#include <ratio>
#include <regex>
#include <scoped_allocator>
#include <system_error>
#include <thread>
#include <tuple>
#include <typeindex>
#include <type_traits>
#include <unordered_map>
#include <unordered_set>

using namespace std;
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define pii pair<int,int>
#define pll pair<long long , long long>
#define vi vector<int>
#define vpii vector<pii>
#define SZ(x) ((int)(x.size()))
#define fi first
#define se second
#define IN(x,y) ((y).find((x))!=(y).end())
#define ALL(t) t.begin(),t.end()
#define FOREACH(i,t) for (typeof(t.begin()) i=t.begin(); i!=t.end(); i++)
#define REP(i,a,b) for(int (i)=(a);(i)<=(b);++i)
#define REPD(i,a,b) for(int (i)=(a); (i)>=(b);--i)
#define FOR(i, n) for (int (i) = 0; (i) < (n); ++(i))
#define dem(x) __builtin_popcount(x)
#define Mask(x) (1LL << (x))
#define BIT(x, i) ((x) >> (i) & 1)
#define ln '\n'
#define io_faster ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
///mt19937 rnd(time(0));

const int INF = 1e9 , mod = 1e9 + 7;

template <class T1, class T2>
inline T1 mul(T1& x, const T2 &k){ return x = (1LL * x * k) % mod; }

template <class T1 , class T2>
inline T1 pw(T1 x, T2 k){T1 res = 1; for (; k ; k >>= 1){ if (k & 1) mul(res, x); mul(x, x); } return res;}

template <class T>
inline bool minimize(T &x, const T &y){ if (x > y){x = y; return 1;} return 0; }

template <class T>
inline bool maximize(T &x, const T &y){ if (x < y){x = y; return 1;} return 0; }

template <class T>
inline void add(T &x , const T &y){ if ((x += y) >= mod) x -= mod; }

template <class T>
inline T product (const T &x , const T &y) { return 1LL * x * y % mod; }

#define PROB "a"
void file(){
    if(fopen(PROB".inp", "r")){
        freopen(PROB".inp","r",stdin);
        freopen(PROB".out","w",stdout);
    }
}
void sinh_(){
//    srand(time(0));
//    freopen(PROB".inp" , "w" , stdout);
//    int n;
}

typedef long long ll;
typedef double db;
const int N = 2e5 + 5;

vpii adj[N];
int dp[N][2], n;
int f[N][2];
int res = 0;

inline void readip(){
    cin >> n;
    REP(i, 2, n) {
        int u, v, c; cin >> u >> v >> c;
        adj[u].eb(v, c);
        adj[v].eb(u, c);
    }
}

inline void dfs_tree(int u, int p = -1) {
    dp[u][0] = 0;
    f[u][0] = f[u][1] = -1e9;
    for (const auto &[v, w] : adj[u]) {
        if (v == p) continue;
        dfs_tree(v, u);

        dp[u][0] += max(w + dp[v][1], dp[v][0]);
        int val = dp[v][0] + w - max(w + dp[v][1], dp[v][0]);
        if (val > f[u][0]) f[u][1] = f[u][0], f[u][0] = val;
        else maximize(f[u][1], val);
   
    }   
    dp[u][1] = dp[u][0] + f[u][0];
}

void reroot(int u, int p) {
    maximize(res, dp[u][0]);
    int dp0 = dp[u][0];
    int dp1 = dp[u][1];

    for (const auto &[v, w] : adj[u]) if (v != p) {
        dp[u][0] -= max(w + dp[v][1] , dp[v][0]);
        if (dp[v][0] + w - max(w + dp[v][1], dp[v][0]) == f[u][0])
            dp[u][1] = dp[u][0] + f[u][1];
        else dp[u][1] = dp[u][0] + f[u][0];
        
        dp[v][0] += max(w + dp[u][1], dp[u][0]);
        
        int val = dp[u][0] + w - max(w + dp[u][1], dp[u][0]);
        if (val > f[v][0]) f[v][1] = f[v][0], f[v][0] = val;
        else maximize(f[v][1], val);
        
        dp[v][1] = dp[v][0] + f[v][0];
        reroot(v, u);

        dp[u][0] = dp0;
        dp[u][1] = dp1;
    }
}

inline void solve(){   
    dfs_tree(1, -1);
    reroot(1, -1);
    cout << res << ln;
}

int main(){
    sinh_();
    io_faster
    file();
    int t = 1;
//    cin >> t;
    while (t--){
        readip();
        solve();
    }
}

컴파일 시 표준 에러 (stderr) 메시지

beads.cpp: In function 'void readip()':
beads.cpp:92:28: warning: unnecessary parentheses in declaration of 'i' [-Wparentheses]
   92 | #define REP(i,a,b) for(int (i)=(a);(i)<=(b);++i)
      |                            ^
beads.cpp:146:5: note: in expansion of macro 'REP'
  146 |     REP(i, 2, n) {
      |     ^~~
beads.cpp: In function 'void dfs_tree(int, int)':
beads.cpp:156:22: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
  156 |     for (const auto &[v, w] : adj[u]) {
      |                      ^
beads.cpp: In function 'void reroot(int, int)':
beads.cpp:174:22: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
  174 |     for (const auto &[v, w] : adj[u]) if (v != p) {
      |                      ^
beads.cpp: In function 'void file()':
beads.cpp:125:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  125 |         freopen(PROB".inp","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
beads.cpp:126:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  126 |         freopen(PROB".out","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 13 / 13
• Subtask 2: 15 / 15
• Subtask 3: 29 / 29
• Subtask 4: 43 / 43