Submission #921321

#	Time	Username	Problem	Language	Result	Execution time	Memory
921321		danikoynov	Shortcut (IOI16_shortcut)	C++14	31 / 100	2028 ms	2004 KiB

shortcut

#include "shortcut.h"
#include <bits/stdc++.h>

using namespace std;
typedef long long ll;

const int maxn = 3010;
const ll inf = 1e18;
int n;
ll cp[maxn], cs[maxn], pref[maxn], bef[maxn], aft[maxn];
ll l[maxn], d[maxn], c;

ll dist[maxn];
struct edge
{
    int to;
    ll w;

    edge(int _to = 0, ll _w = 0)
    {
        to = _to;
        w = _w;
    }

    bool operator < (const edge &e) const
    {
        return w > e.w;
    }
};

int used[maxn];

ll get_dist(int l, int r)
{
    if (l > r)
        swap(l, r);
    return pref[r - 1] - pref[l - 1];
}

const int maxlog = 21;

struct sparse_table
{
    ll dp[maxlog][maxn];
    int lg[maxn];

    void build(vector < ll > values)
    {
        int len = values.size();
        for (int i = 1; i <= len; i ++)
        {
            lg[i] = lg[i / 2]  + 1;
            dp[0][i] = values[i - 1];
        }

        for (int j = 1; j < lg[len]; j ++)
        {
            for (int i = 1; i <= len - (1 << j) + 1; i ++)
            {
                dp[j][i] = dp[j - 1][i + (1 << (j - 1))];
                if (dp[j - 1][i] > dp[j][i])
                    dp[j][i] = dp[j - 1][i];
            }
        }
    }

    ll query(int l, int r)
    {
        if (l > r)
            return 0;
        int mlog = lg[r - l + 1] - 1;
        ll ans = dp[mlog][r - (1 << mlog) + 1];
        if (dp[mlog][l] > ans)
            ans = dp[mlog][l];
        return ans;
    }
};


struct point
{
    ll x, y;

    point(ll _x = 0, ll _y = 0)
    {
        x = _x;
        y = _y;
    }
};
struct rectangle
{
    point centre;
    ll diagonal;

    rectangle(point _centre = point(), ll _diagonal = 0)
    {
        centre = _centre;
        diagonal = _diagonal;
    }
};

ll p[maxn];
bool check(ll x)
{


    vector < rectangle > con;
    for (int i = 1; i <= n; i ++)
    {
        for (int j = i + 1; j <= n; j ++)
        {
            ll path = get_dist(i, j) + d[i] + d[j];
            if (path <= x)
                continue;
            //cout << "condition " << i << " " << j << endl;
            //cout << p[i] << " " << p[j] << " " << x - d[i] - d[j] << endl;
            /// |x[i] - x[l]| + |x[j] - x[r]| + d[i] + d[j] + c<= k
            /// |x[l] - x[i]| + |x[r] - x[j]| <= k - d[i] - d[j] - c
            con.push_back(rectangle(point(p[i], p[j]), x - d[i] - d[j] - c));

        }
    }

    for (int l = 1; l <= n; l ++)
        for (int r = l; r <= n; r ++)
    {
        bool tf = true;
        for (rectangle rec : con)
        {
            ll val = abs(p[l] - rec.centre.x) + abs(p[r] - rec.centre.y);
            if (val > rec.diagonal)
            {
                //cout << "fuck " << l << " " << r << endl;
                //cout << "rectangle " << rec.centre.x << " " << rec.centre.y << " " << rec.diagonal << endl;
                tf = false;
                break;
            }
        }
        if (tf)
        {
            //cout << "works " << l << " " << r << endl;
            return true;
        }
    }

    return false;


}


ll find_shortcut(int N, vector<int> L, vector<int> D, int C)
{
    n = N;
    c = C;
    for (int i = 0; i < n - 1; i ++)
        l[i + 1] = L[i];
    for (int i = 0; i < n; i ++)
        d[i + 1] = D[i];

    p[1] = 0;
    for (int i = 2; i <= n; i ++)
    {
        p[i] = p[i - 1] + l[i - 1];
    }

    for (int i = 1; i <= n; i ++)
    {
        pref[i] = pref[i - 1] + l[i];
    }

    for (int i = 1; i <= n; i ++)
    {
        cp[i] = cp[i - 1] + l[i - 1];
        cp[i] = max(cp[i], d[i]);
        bef[i] = bef[i - 1];
        for (int j = 1; j < i; j ++)
        {
            bef[i] = max(bef[i], get_dist(i, j) + d[i] + d[j]);
        }
    }

    for (int i = n; i > 0; i --)
    {
        cs[i] = cs[i + 1] + l[i];
        cs[i] = max(cs[i], d[i]);
        aft[i] = aft[i + 1];
        for (int j = i + 1; j <= n; j ++)
        {
            aft[i] = max(aft[i], get_dist(i, j) + d[i] + d[j]);
        }
    }




    ll lf = 0, rf = inf;
    while(lf <= rf)
    {
        ll mf = (lf + rf) / 2;
        if (check(mf))
            rf = mf - 1;
        else
            lf = mf + 1;
    }


    return lf;
}

• Subtask 1: 9 / 9
• Subtask 2: 14 / 14
• Subtask 3: 8 / 8
• Subtask 4: 0 / 7
• Subtask 5: 0 / 33
• Subtask 6: 0 / 22
• Subtask 7: 0 / 4
• Subtask 8: 0 / 3