제출 #1243597

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1243597		nvc2k8	The Xana coup (BOI21_xanadu)	C++20	100 / 100	46 ms	26440 KiB

xanadu

#include <bits/stdc++.h>
#define TASK "askdjaskd"
#define endl '\n'
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define BIT(i,x) (((i)>>(x))&1)
#define FOR(i,a,b) for(int i = (a); i<=(b); i++)
#define FORD(i,a,b) for(int i = (a); i>=(b); i--)
#define all(C) C.begin(), C.end()
using namespace std;
using ll = long long;
using pii = pair<int,int>;
const int INT_LIM = 2147483647;
const ll LL_LIM = 9223372036854775807;
template <typename X> bool minimize(X &x, const X &y) {if (x>y){x = y; return true;}return false;}
template <typename X> bool maximize(X &x, const X &y) {if (x<y){x = y; return true;}return false;}
///------------------------------------------///
int n;
int a[100005];
vector<int> adj[100005];

void inp()
{
    cin >> n;
    FOR(i, 1, n-1)
    {
        int u,v;
        cin >> u >> v;
        adj[u].pb(v);
        adj[v].pb(u);
    }
    FOR(i, 1, n) cin >> a[i];
}

int f[100005][2][2];

void calc(int u, int p)
{
    bool leaf = true;
    for (auto v:adj[u]) if (v!=p)
    {
        calc(v, u);
        leaf = false;
    }
    if (leaf)
    {
        f[u][0][a[u]] = 0;
        f[u][1][(a[u]+1)%2] = 1;
        return;
    }

    FOR(d, 0, 1)
    {
        vector<int> pr(2, 0);
        pr[1] = INT_LIM;

        for (auto v:adj[u]) if (v!=p)
        {
            vector<int> g(2, INT_LIM);
            if (f[v][0][d]!=INT_LIM)
            {
                if (pr[0]!=INT_LIM) minimize(g[0], pr[0]+f[v][0][d]);
                if (pr[1]!=INT_LIM) minimize(g[1], pr[1]+f[v][0][d]);
            }
            if (f[v][1][d]!=INT_LIM)
            {
                if (pr[0]!=INT_LIM) minimize(g[1], pr[0]+f[v][1][d]);
                if (pr[1]!=INT_LIM) minimize(g[0], pr[1]+f[v][1][d]);
            }
            pr = g;
        }
        if (pr[0]!=INT_LIM) f[u][d][(a[u]+d+0)%2] = pr[0]+d;
        if (pr[1]!=INT_LIM) f[u][d][(a[u]+d+1)%2] = pr[1]+d;
//        if (u==4) cout << d << ' ' << pr[0] << ' ' << pr[1] << endl;
    }
}

void solve()
{
    FOR(i, 1, n) FOR(j, 0, 1) FOR(k, 0, 1) f[i][j][k] = INT_LIM;
    calc(1, -1);
    int ans = min(f[1][0][0], f[1][1][0]);
    if (ans==INT_LIM) cout << "impossible";
    else cout << ans;
}

signed main()
{
    ///--------------------------///
    ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
    if (fopen(TASK".INP","r")!=NULL)
    {
        freopen(TASK".INP","r",stdin);
        freopen(TASK".OUT","w",stdout);
    }
    ///--------------------------///

    int NTEST = 1;
    bool codeforces = 0;
    if (codeforces) cin >> NTEST;

    while (NTEST--)
    {
        inp();
        solve();
    }

    return 0;
}

///------------------------------------------///

컴파일 시 표준 에러 (stderr) 메시지

xanadu.cpp: In function 'int main()':
xanadu.cpp:95:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   95 |         freopen(TASK".INP","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
xanadu.cpp:96:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   96 |         freopen(TASK".OUT","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 15 / 15
• Subtask 3: 10 / 10
• Subtask 4: 40 / 40
• Subtask 5: 30 / 30