Submission #799962

#	Time	Username	Problem	Language	Result	Execution time	Memory
799962		phoenix	Construction of Highway (JOI18_construction)	C++17	100 / 100	185 ms	20656 KiB

construction

#include<bits/stdc++.h>

using namespace std;
using ll = long long;

const int N = 1e5 + 10;

struct object {
    int color, len;
};
ll numberOfInverse(object *a, int n) {
    static object b[N];

    if(n == 1) return 0;
    ll ans = numberOfInverse(a, n / 2) + numberOfInverse(a + n / 2, (n + 1) / 2);
    int lb = 0, rb = 0, sum = 0;
    for(int i = n / 2; i < n; i++) {
        while(lb < n / 2 && a[lb].color < a[i].color) sum += a[lb++].len;
        ans += 1ll * a[i].len * sum;
    }    
    lb = 0, rb = n / 2;
    for(int i = 0; i < n; i++) {
        if(lb == n / 2) {
            b[i] = a[rb++];
            continue;
        }
        if(rb == n) {
            b[i] = a[lb++];
            continue;
        }
        b[i] = (a[lb].color <= a[rb].color ? a[lb++] : a[rb++]);
    }
    for(int i = 0; i < n; i++) 
        a[i] = b[i];
    return ans;
}

int n;
int C[N];
int sz[N];
int head[N];
int depth[N];
int heavy[N];
int parent[N];

vector<object> v[N];
vector<pair<int, int>> edges;
vector<int> g[N];

void precalc(int s, int p) {
    parent[s] = p; sz[s] = 1;
    for(int to : g[s]) {
        depth[to] = depth[s] + 1;
        precalc(to, s);
        sz[s] += sz[to];
        if(sz[heavy[s]] < sz[to]) heavy[s] = to;
    }
}
void decompose(int s, int h) {
    head[s] = h;
    if(heavy[s]) decompose(heavy[s], h);
    for(int to : g[s]) {
        if(to == heavy[s]) continue;
        decompose(to, to);
    }
    v[h].push_back({C[s], 1});
}

int len = 0;
object t[N]; 

ll query(int a, int x) {
    for(int ver = a; ver; ver = parent[head[ver]]) {
        int u = head[ver];
        int k = depth[ver] - depth[u] + 1;
        vector<object> t1;
        while(v[u].back().len <= k) {
            k -= v[u].back().len;
            t1.push_back(v[u].back());
            v[u].pop_back();
        }
        if(k) {
            object z = {v[u].back().color, k};
            v[u].back().len -= k;
            t1.push_back(z);
            k = 0;
        }
        v[u].push_back({x, depth[ver] - depth[u] + 1});
        while(!t1.empty()) {
            t[len++] = t1.back();
            t1.pop_back();
        }
    }
    // for(int i = 0; i < len; i++) 
    //     cerr << '(' << t[i].color << ' ' << t[i].len << ')' << ' ';
    // cout << '\n';
    ll res = numberOfInverse(t, len);
    len = 0;
    return res;
} 

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0), cout.tie(0);
    cin >> n;
    for(int i = 1; i <= n; i++) cin >> C[i];
    for(int i = 1; i < n; i++) {
        int a, b;
        cin >> a >> b;
        edges.push_back({a, b});
        g[a].push_back(b);
    }
    precalc(1, 0);
    decompose(1, 1);
    for(auto [a, b] : edges) {
        cout << query(a, C[b]) << '\n';
    }
}

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