Submission #102005

#	Time	Username	Problem	Language	Result	Execution time	Memory
102005		naoai	Ideal city (IOI12_city)	C++14	55 / 100	214 ms	16108 KiB

city

#include <bits/stdc++.h>

using namespace std;

typedef long long i64;
const int mod = 1e9;
const int nmax = 1e5;

const int dl[4] = {-1, 0, 0, 1};
const int dc[4] = {0, -1, 1, 0};

queue<pair<int, int>> q;
bool viz[2000 + 1];

int ind[2000 + 1][2000 + 1];

int brut (int N, int *X, int *Y) {
    int mnx = 1 << 30;
    int mny = 1 << 30;

    for (int i = 0; i < N; ++ i) {
        mnx = min(mnx, X[i]);
        mny = min(mny, Y[i]);
    }

    for (int i = 0; i < N +1; ++ i)
        for (int j = 0; j < N + 1; ++ j)
            ind[i][j] = -1;

    for (int i = 0; i < N; ++ i) {
        X[i] -= (mnx - 1);
        Y[i] -= (mny - 1);
        ind[X[i]][Y[i]] = i;
    }

    i64 ans = 0;
    for (int i = 0; i < N; ++ i) {
        memset(viz, 0, sizeof(viz));
        q.push({i, 0});
        viz[i] = 1;

        while (!q.empty()) {
            int x = q.front().first;
            int y = q.front().second;
            q.pop();
            ans += y;

            for (int k = 0; k <4; ++ k) {
                int a = X[x] + dl[k], b = Y[x] + dc[k];
                if (ind[a][b] != -1) {
                    int t = ind[a][b];
                    if (viz[t] == 1)
                        continue;

                    viz[t] = 1;
                    q.push({t, y + 1});
                }
            }
        }
    }

    ans /= 2;
    return ans % mod;
}

i64 solve (vector<int> &v) {
    sort(v.begin(), v.end());

    i64 ans = 0;
    i64 sum = 0;
    for (auto i : v)
        sum += i;

    i64 m = 0;
    for (int i = 0; i < v.size(); ++ i) {
        sum -= v[i];

        ans += 1LL * v[i] * i - m + sum - 1LL * v[i] * (v.size() - 1 - i);

        m += v[i];
    }
    return ans;
}

int DistanceSum(int N, int *X, int *Y) {
    if (N <= 2000) {
        return brut(N, X, Y);
    } else {
        i64 ans = 0;

        vector<int> v;
        for (int i = 0; i < N; ++ i)
            v.push_back(X[i]);
        ans += solve(v);

        v.clear();
        for (int i = 0; i < N; ++ i)
            v.push_back(Y[i]);
        ans += solve(v);

        return (ans / 2) % mod;
    }
}

Compilation message (stderr)

city.cpp: In function 'i64 solve(std::vector<int>&)':
city.cpp:75:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < v.size(); ++ i) {
                     ~~^~~~~~~~~~

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