제출 #1118278

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1118278		smokieboi	Museum (CEOI17_museum)	C++17	100 / 100	314 ms	785320 KiB

museum

#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define nl '\n'
#define fu(i,a,b) for(int i=a; i<=b; i++)
#define fd(i,a,b) for(int i=a; i>=b; i--)
#define BIT(i, n) (((n)>>(i))&(1))
#define pii pair<int, int>
#define ff first
#define ss second
#define all(v) v.begin(), v.end()
#define SZ(V) (int)(V.size())
#define pb push_back
#define eb emplace_back
#define NAME "quan"

int t,n,m,k,q;

const int N = 1e4 + 5;
const int MOD = 1e9 + 7;
const int inf = 2e9 + 7;

void add(int &a, int b) {a+=b; if(a>=MOD) a-=MOD;}
void sub(int &a, int b) {a-=b; if(a<0) a+=MOD;}

// dp[u][k][0/1] : số bước ít nhất để đi được k đỉnh ở subtree u và có quay lại u hay không

int sz[N];
int dp[N][N][2];
vector<pii> adj[N];
int root;

void dfs(int u, int p){
    dp[u][1][0] = dp[u][1][1] = 0;
    sz[u] = 1;
    for(pii it: adj[u]){
        int v = it.ff;
        int w = it.ss;
        if(v == p) continue;
        dfs(v, u);
        fd(i,sz[u],1)
            fd(j,sz[v],1){
                dp[u][i + j][0] = min(dp[u][i + j][0], dp[u][i][1] + dp[v][j][0] + w);
                dp[u][i + j][0] = min(dp[u][i + j][0], dp[u][i][0] + dp[v][j][1] + 2*w);
                dp[u][i + j][1] = min(dp[u][i + j][1], dp[u][i][1] + dp[v][j][1] + 2*w);
            }
        sz[u] += sz[v];
    }
}

void nhap(){
    cin >> n >> k >> root;
    fu(i,1,n-1){
        int u,v,w;
        cin >> u >> v >> w;
        adj[u].eb(v, w);
        adj[v].eb(u, w);
    }
    memset(dp, 0x3f, sizeof dp);
    dfs(root, 0);
    cout << dp[root][k][0] << nl;
}

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    if(fopen(NAME".inp", "r")){
       freopen(NAME".inp", "r", stdin);
       freopen(NAME".out", "w", stdout);
    }
    nhap();
}

컴파일 시 표준 에러 (stderr) 메시지

museum.cpp: In function 'int main()':
museum.cpp:69:15: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   69 |        freopen(NAME".inp", "r", stdin);
      |        ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
museum.cpp:70:15: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   70 |        freopen(NAME".out", "w", stdout);
      |        ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 20 / 20
• Subtask 2: 25 / 25
• Subtask 3: 35 / 35
• Subtask 4: 20 / 20