Submission #403311

#	Time	Username	Problem	Language	Result	Execution time	Memory
403311		Leonardo_Paes	The Xana coup (BOI21_xanadu)	C++17	100 / 100	91 ms	24452 KiB

xanadu

#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5+10, inf = 0x3f3f3f3f;
bool s[maxn];
int dp[maxn][2][2], aux[maxn][2][2];
vector<int> grafo[maxn];
void solve(int u, int p = 0){
    for(int i : {0, 1}){
        for(int j : {0, 1}){
            dp[u][i][j] = (s[u] ^ i == j ? i : inf);
        }
    }
    for(int v : grafo[u]){
        if(v == p) continue;
        solve(v, u);
        for(int i : {0, 1}){ // ligo ou nao o u
            for(int j : {0, 1}){ // vou ficar ligado ou n dependendo da minha subarvore
                for(int k : {0, 1}){
                    for(int l : {0, 1}){
                        if(i^l) continue; // n pode
                        aux[u][i][j^k] = min(aux[u][i][j^k], dp[u][i][j] + dp[v][k][l]);
                    }
                }
            }
        }
        for(int i : {0, 1}){
            for(int j : {0, 1}){
                dp[u][i][j] = aux[u][i][j];
                aux[u][i][j] = inf;
            }
        }
    }
}
int main(){
    ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
    memset(aux, inf, sizeof aux);
    int n;
    cin >> n;
    for(int i=1; i<n; i++){
        int u, v;
        cin >> u >> v;
        grafo[u].push_back(v);
        grafo[v].push_back(u);
    }
    for(int i=1; i<=n; i++) cin >> s[i];
    solve(1);
    int ans = min(dp[1][0][0], dp[1][1][0]);
    if(ans == inf) cout << "impossible\n";
    else cout << ans << "\n";
    return 0;
}

Compilation message (stderr)

xanadu.cpp: In function 'void solve(int, int)':
xanadu.cpp:10:37: warning: suggest parentheses around comparison in operand of '^' [-Wparentheses]
   10 |             dp[u][i][j] = (s[u] ^ i == j ? i : inf);
      |                                   ~~^~~~

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