Submission #701167

#	Time	Username	Problem	Language	Result	Execution time	Memory
701167		Do_you_copy	Zagrade (COI17_zagrade)	C++17	100 / 100	1220 ms	47996 KiB

zagrade

#include <bits/stdc++.h>
#define fi first
#define se second
#define faster ios_base::sync_with_stdio(0); cin.tie(0);
#define pb push_back

using namespace std;
using ll = long long;
using pii = pair <int, int>;

const int maxN = 3e5 + 100;
const int inf = 0x3f3f3f3f;
//const int Mod =
string s;
int n;
bool visited[maxN];
int sz[maxN];
int cnt[maxN];
vector <int> adj[maxN];
int a[maxN];
void pre_dfs(int u, int p){
    sz[u] = 1;
    for (int i: adj[u]){
        if (i == p || visited[i]) continue;
        pre_dfs(i, u);
        sz[u] += sz[i];
    }
}

int find_cent(int u, int p, int szz){
    for (int i: adj[u]){
        if (i == p || visited[i]) continue;
        if (sz[i] > szz / 2) return find_cent(i, u, szz);
    }
    return u;
}

ll ans = 0;
void dfs(int u, int p, int t, int d, int minn){
    //t == 0: calculate
    //t == 1: add
    //t == 2: delete
    if (t == 0){
        minn = min(minn, d);
        //if (u == 4 && p == 2) cerr << d << " " << minn << "\n";
        if (minn == d){
            ans += cnt[-minn];
        }
    }
    if (t == 1){
        minn = min(minn + a[u], a[u]);
        if (minn >= 0) ++cnt[d];
    }
    if (t == 2){
        minn = min(minn + a[u], a[u]);
        if (minn >= 0) --cnt[d];
    }
    for (int i: adj[u]){
        if (i == p || visited[i]) continue;
        dfs(i, u, t, d + a[i], minn);
    }
}

void update(int u){
    //if (u == 2) cerr << a[4] << ":D";
    if (a[u] == 1) cnt[1] = 1;
    for (int i: adj[u]){
        if (visited[i]) continue;
        dfs(i, u, 0, a[i], 0);
        dfs(i, u, 1, a[u] + a[i], a[u]);
    }
    for (int i: adj[u]){
        if (visited[i]) continue;
        dfs(i, u, 2, a[u] + a[i], a[u]);
    }
    if (a[u] == 1) cnt[1] = 0;
}

void build_cent(int u){
    pre_dfs(u, u);
    int cent = find_cent(u, u, sz[u]);
    //cerr << cent << "\n";
    visited[cent] = 1;
    update(cent);
    for (int i: adj[cent]){
        if (visited[i]) continue;
        build_cent(i);
    }
}

void Init(){
    cin >> n;
    cin >> s;
    s = " " + s;
    for (int i = 1; i <= n; ++i){
        if (s[i] == '(') a[i] = 1;
        else a[i] = -1;
    }
    for (int i = 1; i < n; ++i){
        int u, v;
        cin >> u >> v;
        adj[u].pb(v);
        adj[v].pb(u);
    }
    build_cent(1);
    fill(visited + 1, visited + 1 + n, 0);
    for (int i = 1; i <= n; ++i) a[i] = -a[i];
    build_cent(1);
    cout << ans;

}

#define taskname "test"
signed main(){
    faster
    if (fopen(taskname ".inp", "r")){
        freopen(taskname ".inp", "r", stdin);
        freopen(taskname ".out", "w", stdout);
    }
    int tt = 1;
    //cin >> tt;
    while (tt--){
        Init();
    }
    if (fopen("timeout.txt", "r")){
        ofstream timeout("timeout.txt");
        cerr << "Time elapsed: " << signed(double(clock()) / CLOCKS_PER_SEC * 1000) << "ms\n";
        timeout << signed(double(clock()) / CLOCKS_PER_SEC * 1000);
        timeout.close();
    }
}

Compilation message (stderr)

zagrade.cpp: In function 'int main()':
zagrade.cpp:117:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  117 |         freopen(taskname ".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
zagrade.cpp:118:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  118 |         freopen(taskname ".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 30 / 30
• Subtask 3: 60 / 60