Submission #1123157

#	Time	Username	Problem	Language	Result	Execution time	Memory
1123157		Yang8on	Construction of Highway (JOI18_construction)	C++17	100 / 100	237 ms	20164 KiB

construction

#include <bits/stdc++.h>
#define Y8o "main"
#define maxn (int) 1e5 + 5
#define ll long long
#define pii pair<int, int>
#define gb(i, j) ((i >> j) & 1)
#define all(x) x.begin(), x.end()
#define _left id * 2, l, mid
#define _right id * 2 + 1, mid + 1, r
#define fi(i, a, b) for(int i = a; i <= b; i ++)
#define fid(i, a, b) for(int i = a; i >= b; i --)

#define f first
#define s second

using namespace std;

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
ll GetRandom(ll l, ll r) {
    return uniform_int_distribution<ll> (l, r) (rng);
}
void iof() {
    ios_base::sync_with_stdio(0);
    cin.tie(NULL), cout.tie(NULL);
    if(fopen(Y8o".inp", "r"))
    {
        freopen(Y8o".inp", "r", stdin);
//        freopen(Y8o".out", "w", stdout);
    }
}
void ctime() {
    cerr << "\n" << "\nTime elapsed: " << 1000 * clock() / CLOCKS_PER_SEC << "ms\n";
}

int n; ll ans;
int a[maxn];
pii ed[maxn];
vector<int> o[maxn], cur;
int sz[maxn];
int h[maxn], nex[maxn], par[maxn];
int in[maxn], out[maxn], cnt;
vector<pii> child[maxn];

struct BIT {
    int bit[maxn];
    void update(int x, int val) {
        while(x > 0) bit[x] += val, x -= (x & -x);
    }
    int get(int x, int sum = 0) {
        while(x <= n) sum += bit[x], x += (x & -x);
        return sum;
    }
} Bit;

void pre_dfs(int u = 1, int p = 0) {
    sz[u] = 1;
    for(int &v : o[u]) {
        o[v].erase(find(all(o[v]), u));
        pre_dfs(v, u);
        if(sz[v] > sz[o[u][0]]) swap(v, o[u][0]);
        sz[u] += sz[v];
    }
}

void dfs(int u = 1) {
    in[u] = ++cnt;
    for(int v : o[u]) {
        h[v] = h[u] + 1, par[v] = u;
        nex[v] = v == o[u][0] ? nex[u] : v;
        dfs(v);
    }
}

void prog(int p, int u, int val, vector<pii>& st) {
    int pre = h[p] - 1;
    vector<pii> tmp;

    while(child[p].size() && h[child[p].back().f] < h[u]) {
        tmp.push_back({ child[p].back().s, h[child[p].back().f] - pre });
        pre = h[child[p].back().f];
        child[p].pop_back();
    }
    if(child[p].size()) tmp.push_back({ child[p].back().s, h[u] - pre });
    child[p].push_back({ u, val });

    reverse(all(tmp));
    for(pii x : tmp) st.push_back(x);
}

void update(int u, int val) {
    vector<pii> st;
    while(u != 0) {
        prog(nex[u], u, val, st);
        u = par[nex[u]];
    }
    reverse(all(st));

    for(auto [cl, sl] : st) ans += 1ll * sl * Bit.get(cl), Bit.update(cl - 1, +sl);
    for(auto [cl, sl] : st) Bit.update(cl - 1, -sl);
}

void solve() {
    cin >> n;
    fi(i, 1, n) cin >> a[i], cur.push_back(a[i]);
    sort(all(cur));
    cur.resize( unique(all(cur)) - cur.begin() );
    fi(i, 1, n) a[i] = lower_bound(all(cur), a[i]) - cur.begin() + 1;

    fi(i, 1, n - 1) {
        int u, v; cin >> u >> v;
        o[u].push_back(v), o[v].push_back(u);
        ed[i] = { u, v };
    }

    nex[1] = 1;
    pre_dfs(), dfs();
    update(1, a[1]);

    fi(i, 1, n - 1) {
        int u, v; tie(u, v) = ed[i];
        ans = 0, update(v, a[v]);
        cout << ans << '\n';
    }
}

int main() {
    iof();

    int nTest = 1;
//    cin >> nTest;

    while(nTest --) {
        solve();
    }

    ctime();
    return 0;
}

Compilation message (stderr)

construction.cpp: In function 'void iof()':
construction.cpp:27:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   27 |         freopen(Y8o".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 7 / 7
• Subtask 2: 9 / 9
• Subtask 3: 84 / 84