Submission #250881

#	Time	Username	Problem	Language	Result	Execution time	Memory
250881		VEGAnn	Zagrade (COI17_zagrade)	C++14	40 / 100	3088 ms	44960 KiB

zagrade

#include <bits/stdc++.h>
//#pragma GCC optimize("unroll-loops")
//#pragma GCC optimize("-O3")
//#pragma GCC optimize("Ofast")
//#pragma GCC optimize("fast-math")
//#pragma GCC optimize("no-stack-protector")
#define PB push_back
#define all(x) x.begin(),x.end()
using namespace std;
typedef long long ll;
const int N = 300100;
vector<int> g[N];
ll ans;
int n, siz[N], ad[N], sta[N], ed[N], mn_sta[N], mn_ed[N], mem[N];
bool used[N];
string s;

void build_sz(int v, int p){
    siz[v] = 1;

    for (int u : g[v]){
        if (u == p || used[v]) continue;

        build_sz(u, v);

        siz[v] += siz[u];
    }
}

int search(int v, int pr, int SZ){
    for (int u : g[v]){
        if (u == pr || used[u]) continue;

        if (siz[u] > SZ / 2)
            return search(u, v, SZ);
    }

    return v;
}

void dfs(int v, int pr){
    mn_sta[v] = min(mn_sta[pr] + ad[v], 0);
    mn_ed[v] = min(mn_ed[pr] - ad[v], 0);

    sta[v] = sta[pr] + ad[v];
    ed[v] = ed[pr] + ad[v];

    for (int u : g[v]){
        if (used[u] || u == pr) continue;

        dfs(u, v);
    }
}

void calc(int v, int pr){
    if (mn_sta[v] == 0)
        ans += mem[sta[v]];

    for (int u : g[v]){
        if (used[u] || u == pr) continue;

        calc(u, v);
    }
}

void upda(int v, int pr){
    if (mn_ed[v] == 0)
        mem[-ed[v]]++;

    for (int u : g[v]){
        if (used[u] || u == pr) continue;

        upda(u, v);
    }
}

void build_cd(int v){
    build_sz(v, -1);

    int SZ = siz[v];
    int cen = search(v, -1, siz[v]);

    used[cen] = 1;

    // calc subtree sums

    sta[cen] = 0;
    ed[cen] = ad[cen];

    mn_ed[cen] = min(0, -ad[cen]);
    mn_sta[cen] = 0;

    for (int u : g[cen]){
        if (used[u]) continue;

        dfs(u, cen);
    }

    // update ans (left, right)

    //left

    fill(mem, mem + SZ + 1, 0);

    if (mn_ed[cen] == 0)
        mem[-ed[cen]]++;

    for (int u : g[cen]){
        if (used[u]) continue;

        calc(u, cen);
        upda(u, cen);
    }

    //right

    fill(mem, mem + SZ + 1, 0);

    reverse(all(g[cen]));

    for (int u : g[cen]){
        if (used[u]) continue;

        calc(u, cen);
        upda(u, cen);
    }

    if (mn_sta[cen] == 0)
        ans += mem[sta[cen]];

    // continue process in children subtrees

    for (int u : g[cen])
        if (!used[u])
            build_cd(u);
}

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

#ifdef _LOCAL
    freopen("in.txt","r",stdin);
#endif // _LOCAL

    cin >> n >> s;

    for (int i = 0; i < n; i++){
        if (s[i] == '(')
            ad[i] = 1;
        else ad[i] = -1;
    }

    for (int i = 1; i < n; i++) {
        int x, y; cin >> x >> y;
        x--; y--;

        g[x].PB(y);
        g[y].PB(x);
    }

    build_cd(0);

    cout << ans;

    return 0;
}

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