Submission #1100978

#	Time	Username	Problem	Language	Result	Execution time	Memory
1100978		lmToT27	Svjetlo (COCI20_svjetlo)	C++17	110 / 110	235 ms	97924 KiB

svjetlo

#include <bits/stdc++.h>
#define all(dataStructure) dataStructure.begin(),dataStructure.end()
#define ll long long

using namespace std;
namespace std {
        template <typename T, int D>
        struct _vector : public vector <_vector <T, D - 1>> {
                static_assert(D >= 1, "Dimension must be positive!");
                template <typename... Args>
                _vector(int n = 0, Args... args) : vector <_vector <T, D - 1>> (n, _vector <T, D - 1> (args...)) {}
        };
        // _vector <int, 3> a(n, m, k);: int a[n][m][k].
        // _vector <int, 3> a(n, m, k, x);: int a[n][m][k] initialized with x.
        template <typename T>
        struct _vector <T, 1> : public vector <T> {
                _vector(int n = 0, const T& val = T()) : vector <T> (n, val) {}
        };

        template <typename T>
        T _min(T a) {
                return a;
        }

        template <typename T, typename... Args>
        T _min(T a, Args... args) {
                return min(a, _min(args...));
        }
}

const int MAX = 5e5 + 3;
const ll MOD[] = {1000000007, 998244353};

int n, sz[MAX];
string s;
vector <int> adj[MAX];
int dp[MAX][2][3];
int nDp[2][3];

void dfs(int u, int pre) {
        sz[u] = s[u] == '0';
        for (int &v : adj[u]) {
                if (v != pre) {
                        dfs(v, u);
                        sz[u] += sz[v];
                }
        }

        if (!sz[u]) return;

        int x = s[u] - '0';
        dp[u][x ^ 1][0] = dp[u][x ^ 1][1] = dp[u][x ^ 1][2] = 1;

        for (int &v : adj[u]) {
                if (v == pre || sz[v] == 0) continue;

                memset(nDp, 0x0f, sizeof nDp);
                auto &dp = ::dp[u];
                auto &f = ::dp[v];
                for (int i = 0; i < 2; i++) {
                        nDp[i][0] = _min(dp[i ^ 1][0] + f[1][0] + 1, dp[i][0] + f[0][0] + 3);
                        nDp[i][1] = _min(dp[i ^ 1][1] + f[1][0] + 1, dp[i ^ 1][0] + f[0][1] + 2,
                                        dp[i][1] + f[0][0] + 3, dp[i][0] + f[1][1]);
                        nDp[i][2] = _min(dp[i][1] + f[1][1], dp[i ^ 1][1] + f[0][1] + 2,
                                        dp[i ^ 1][2] + f[1][0] + 1, dp[i][2] + f[0][0] + 3,     
                                        dp[i ^ 1][0] + f[1][2] + 3, dp[i][0] + f[0][2] + 1);
                        nDp[i][1] = _min(nDp[i][1], nDp[i][0]);
                        nDp[i][2] = _min(nDp[i][2], nDp[i][1]);
                }
                swap(dp, nDp);
        }
}

void Solve() {
        cin >> n;
        cin >> s;
        s = '#' + s;
        for (int i = 1; i < n; i++) {
                int u, v;
                cin >> u >> v;
                adj[u].push_back(v);
                adj[v].push_back(u);
        }

        memset(dp, 0x0f, sizeof dp);
        
        for (int i = 1; i <= n; i++) {
                if (s[i] == '0') {
                        dfs(i, 0);
                        cout << dp[i][1][2];
                        return;
                }
        }

        cout << 0;
}

int32_t main() {
        ios_base::sync_with_stdio(0);
        cin.tie(0);

        #define TASK "TASK"
        if (fopen(TASK".INP", "r")) {
                freopen(TASK".INP", "r", stdin);
                freopen(TASK".OUT", "w", stdout);
        }
        
        /* int TEST = 1; cin >> TEST; while (TEST--) */ Solve();

        cerr << "\nTime elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << "s\n";
        return 0;
}

Compilation message (stderr)

svjetlo.cpp: In function 'int32_t main()':
svjetlo.cpp:104:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  104 |                 freopen(TASK".INP", "r", stdin);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
svjetlo.cpp:105:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  105 |                 freopen(TASK".OUT", "w", stdout);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 20 / 20
• Subtask 2: 30 / 30
• Subtask 3: 30 / 30
• Subtask 4: 30 / 30