Submission #1031281

#	Time	Username	Problem	Language	Result	Execution time	Memory
1031281		VMaksimoski008	Ideal city (IOI12_city)	C++17	100 / 100	42 ms	9004 KiB

city

#include "bits/stdc++.h"
using namespace std;
using ll = long long;
using pii = pair<int, int>;
const int maxn = 1e5 + 5;
const int mod = 1e9;

vector<int> graph[maxn];
vector<ll> sub(maxn), sz(maxn);

void dfs(int u, int p) {
    sub[u] = sz[u];
    for(int &v : graph[u]) {
        if(v == p) continue;
        dfs(v, u);
        // cout << u << " -> " << v << '\n';
        sub[u] += sub[v];
    }
}

ll solve(vector<pii> v, int N, int *X, int *Y) {
    for(int i=0; i<maxn; i++) {
        graph[i].clear();
        sub[i] = sz[i] = 0;
    }

    int mn = 1e9, mx = 0;
    for(int i=0; i<N; i++) {
        mn = min(mn, v[i].first);
        mx = max(mx, v[i].first);
    }

    int curr = 1, p = 0, start = 0;

    vector<array<int, 3> > ivals;
    for(int i=mn; i<=mx; i++) {
        start = p;
        int last = v[p].second-1;
        vector<array<int, 3> > nvals;
        int ptr = 0;
        while(p < N && v[p].first == i) {
            if(v[p].second - last > 1) {
                for(auto &[L, r, id] : ivals) {
                    if(min(r, v[p-1].second) - max(L, v[start].second) >= 0) {
                        graph[id].push_back(curr);
                        graph[curr].push_back(id);
                    }   
                }
                nvals.push_back({ v[start].second, v[p-1].second, curr });
                start = p;
                curr++;
            }
            sz[curr]++;
            last = v[p].second;
            p++;
        }

        if(start < p) {
            for(auto &[L, r, id] : ivals) {
                if(min(r, v[p-1].second) - max(L, v[start].second) >= 0) {
                    graph[id].push_back(curr);
                    graph[curr].push_back(id);
                }
            }
            nvals.push_back({ v[start].second, v[p-1].second, curr });
            start = p;
        }

        curr++;
        ivals = nvals;
    }

    dfs(1, 1);
    ll ans = 0;
    for(int i=2; i<curr; i++) ans = (ans + sub[i] % mod * ((ll)N - sub[i]) % mod) % mod;
    return ans;
}

int DistanceSum(int N, int *X, int *Y) {
    vector<pii> v;
    for(int i=0; i<N; i++) v.push_back({ X[i], Y[i] });
    sort(v.begin(), v.end());

    ll ans = solve(v, N, X, Y);

    for(int i=0; i<N; i++) swap(v[i].first, v[i].second);
    sort(v.begin(), v.end());

    return (ans + solve(v, N, X, Y)) % mod;
}

Compilation message (stderr)

city.cpp: In function 'll solve(std::vector<std::pair<int, int> >, int, int*, int*)':
city.cpp:40:13: warning: unused variable 'ptr' [-Wunused-variable]
   40 |         int ptr = 0;
      |             ^~~

• Subtask 1: 11 / 11
• Subtask 2: 21 / 21
• Subtask 3: 23 / 23
• Subtask 4: 45 / 45