Submission #97492

#	Time	Username	Problem	Language	Result	Execution time	Memory
97492		Alexa2001	Ideal city (IOI12_city)	C++17	55 / 100	184 ms	6236 KiB

city

#include <bits/stdc++.h>

using namespace std;

const int Mod = 1e9, Nmax = 1e5 + 5;
typedef long long ll;

int n, x[Nmax], y[Nmax], A[2005][2005], d[2005][2005];

class AIB
{
    ll a[Nmax]; int b[Nmax];
    int ub(int x) { return (x&(-x)); }

public:
    int query(int x)
    {
        ll sum1 = 0, sum2 = 0;
        int cnt1 = 0, cnt2 = 0;
        int i;

        for(i=x; i; i-=ub(i))
            sum1 += a[i], cnt1 += b[i];

        for(i=n; i; i-=ub(i))
            sum2 += a[i], cnt2 += b[i];

        sum2 -= sum1, cnt2 -= cnt1;

        sum1 = (ll) x * cnt1 - sum1;
        sum2 = sum2 - (ll) x * cnt2;
        return (sum1 + sum2) % Mod;
    }

    void update(int pos)
    {
        int i;
        for(i=pos; i<=n; i+=ub(i))
            a[i] += pos, b[i] ++;
    }
} aib;

int solve1()
{
    int i;
    vector<int> p[Nmax];
    for(i=0; i<n; ++i) p[x[i]].push_back(y[i]);

    ll sumx = 0, cnt = 0, ans = 0;

    for(i=1; i<=n; ++i)
        for(auto it : p[i])
        {
            ans += aib.query(it);
            ans %= Mod;
            aib.update(it);

            ans += (ll) i * cnt - sumx;
            ans %= Mod;

            ++cnt; sumx += i;
        }
    return (int)ans;
}

void bfs(int x, int y)
{
    queue< pair<int,int> > q;
    q.push({x, y});
    d[x][y] = 0;
    while(q.size())
    {
        tie(x, y) = q.front();
        q.pop();

        if(A[x-1][y] && d[x-1][y] == -1)
        {
            d[x-1][y] = d[x][y] + 1;
            q.push({x-1, y});
        }
        if(A[x+1][y] && d[x+1][y] == -1)
        {
            d[x+1][y] = d[x][y] + 1;
            q.push({x+1, y});
        }
        if(A[x][y-1] && d[x][y-1] == -1)
        {
            d[x][y-1] = d[x][y] + 1;
            q.push({x, y-1});
        }
        if(A[x][y+1] && d[x][y+1] == -1)
        {
            d[x][y+1] = d[x][y] + 1;
            q.push({x, y+1});
        }
    }
}

int DistanceSum(int N, int *X, int *Y)
{
    int i, j, xmin = 2e9, ymin = 2e9; n = N;
    for(i=0; i<N; ++i)
    {
        x[i] = X[i];
        y[i] = Y[i];
        xmin = min(xmin, x[i]);
        ymin = min(ymin, y[i]);
    }

    for(i=0; i<N; ++i)
        x[i] -= xmin - 1, y[i] -= ymin - 1;

    if(N > 2000)
        return solve1();

  //    cerr << solve1() << '\n';

    ll ans = 0;

    for(i=0; i<n; ++i) A[x[i]][y[i]] = 1;

    for(i=0; i<n; ++i)
    {
        for(j=0; j<n; ++j) d[x[j]][y[j]] = -1;
        bfs(x[i], y[i]);
        for(j=i+1; j<n; ++j) ans += d[x[j]][y[j]];
        ans %= Mod;
    }
    return ans;
}

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