Submission #1019588

#	Time	Username	Problem	Language	Result	Execution time	Memory
1019588		vjudge1	Zagrade (COI17_zagrade)	C++17	10 / 100	3104 ms	46008 KiB

zagrade

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

#define ll long long
#define ld long double
#define ull unsigned long long
#define pii pair<int,int>
#define pll pair<long long, long long>
#define fi first
#define se second
#define all(a) (a).begin(), (a).end()
#define pb push_back
#define lwb lower_bound
#define upb upper_bound

#define TASKNAME "NAME"

void init()
{
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    ///freopen(TASKNAME".INP","r",stdin); freopen(TASKNAME".OUT","w",stdout);
}

const int SZ = 3e5+5;
const ll INF = INT_MAX / 2, MOD = 1e9+7, INFLL = 2e18;
const double epsilon = 1e-3;

int n, a[SZ];
string s;
vector<int> adj[SZ];
ll res = 0;
bool del[SZ];

void dfsSize(int u, int pre)
{
    s[u] = 1;
    for(int v : adj[u])
    {
        if(v == pre || del[v]) continue;
        dfsSize(v,u);
        s[u] += s[v];
    }
}

int findCentroid(int u, int pre, int treeSize)
{
    for(int v : adj[u])
    {
        if(v == pre || del[v]) continue;
        if(s[v] > treeSize / 2) return findCentroid(v, u, treeSize);
    }
    return u;
}

int cnt[SZ];

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){
            res += 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 || del[i]) continue;
        dfs(i, u, t, d + a[i], minn);
    }
}

void updateRes(int root)
{
    if(a[root] == 1) cnt[1] = 1;
    for(int u : adj[root])
    {
        if(del[u]) continue;
        dfs(u, root, 0, a[u], 0);
        dfs(u, root, 1, a[root] + a[u], a[root]);
    }
    for(int u : adj[root])
    {
        if(del[u]) continue;
        dfs(u, root, 2, a[root] + a[u], a[root]);
    }
    if (a[root] == 1) cnt[1] = 0;
}

void solve(int u)
{
    dfsSize(u,0);
    int root = findCentroid(u, 0, s[u]);
    del[root] = true;
    ll preres = res;
    updateRes(root);
    //cout << root << " - " << res - preres << '\n';
    for(int v : adj[root])
    {
        if(del[v]) continue;
        solve(v);
    }
}

int main()
{
    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);
    }
    solve(1);
    for(int i = 1; i <= n; i++)
    {
        if(a[i] == 1) a[i] = -1;
        else a[i] = 1;
    }
    memset(del, false, sizeof(del));
    solve(1);
    cout << res;
}

Compilation message (stderr)

zagrade.cpp: In function 'void solve(int)':
zagrade.cpp:104:8: warning: unused variable 'preres' [-Wunused-variable]
  104 |     ll preres = res;
      |        ^~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 0 / 30
• Subtask 3: 0 / 60