Submission #448004

#	Time	Username	Problem	Language	Result	Execution time	Memory
448004		dxz05	Ideal city (IOI12_city)	C++14	55 / 100	140 ms	6700 KiB

city

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

const int MOD = 1e9;
const int MAXN = 2e5 + 3e2;

vector<int> g[MAXN];

vector<int> dx = {0, 1, 0, -1}, dy = {1, 0, -1, 0};

int DistanceSum(int N, int *X, int *Y) {
    if (N <= 2000) {
        map<pair<int, int>, int> mp;
        for (int i = 0; i < N; i++) {
            mp[{X[i], Y[i]}] = i;
        }

        for (int i = 0; i < N; i++) {
            for (int j = 0; j < 4; j++) {
                if (mp.find({X[i] + dx[j], Y[i] + dy[j]}) != mp.end()) {
                    g[i].push_back(mp[{X[i] + dx[j], Y[i] + dy[j]}]);
                }
            }
        }

        ll ans = 0;

        for (int i = 0; i < N; i++) {
            queue<int> q;
            q.push(i);

            vector<int> d(N, 1e9);
            d[i] = 0;

            while (!q.empty()) {
                int x = q.front();
                q.pop();
                ans += d[x];

                for (int y : g[x]) {
                    if (d[y] == 1e9) {
                        d[y] = d[x] + 1;
                        q.push(y);
                    }
                }
            }

        }

        ans >>= 1;

        return ans % MOD;
    }

    sort(X, X + N);
    sort(Y, Y + N);

    ll ans = 0;

    ll lf = 0, rg = accumulate(X, X + N, 0ll);
    for (int i = 0; i < N; i++){
        rg -= X[i];
        ans += 1ll * i * X[i] - lf;
        ans += rg - 1ll * (N - i - 1) * X[i];
        lf += X[i];
    }

    lf = 0, rg = accumulate(Y, Y + N, 0ll);
    for (int i = 0; i < N; i++){
        rg -= Y[i];
        ans += 1ll * i * Y[i] - lf;
        ans += rg - 1ll * (N - i - 1) * Y[i];
        lf += Y[i];
    }

    ans >>= 1;
    return ans % MOD;
}

/*

7
3 3
4 3
4 4
4 5
4 6
5 3
5 4

*/

• Subtask 1: 11 / 11
• Subtask 2: 21 / 21
• Subtask 3: 23 / 23
• Subtask 4: 0 / 45