Submission #692696

#	Time	Username	Problem	Language	Result	Execution time	Memory
692696		zeroesandones	Lightning Rod (NOI18_lightningrod)	C++17	66 / 100	1261 ms	262144 KiB

Main

#include "bits/stdc++.h"
using namespace std;

typedef long long ll;
typedef long double ld;
typedef vector<ll> vi;
typedef pair<ll, ll> pi;

#define FOR(i, j, k) for (ll i = j; i < (ll) k; ++i)
#define FORD(i, j, k) for (ll i = j; i >= (ll) k; --i)
#define nl "\n"
#define sp " "

#define all(x) (x).begin(), (x).end()
#define sc second
#define fr first
#define pb emplace_back

struct BIT {
    ll n;
    vi tree;

    BIT(ll N) {
        n = N;
        tree.resize(n, 0);
    }

    void add(ll x, ll k) {
        while(k <= n) {
            tree[k] += x;
            k += k&-k;
        }
    }

    ll get(ll k) {
        ll sum = 0;
        while(k >= 1) {
            sum += tree[k];
            k -= k&-k;
        }

        return sum;
    }
};

void solve()
{
    ll n;
    cin >> n;

    ll x[n + 1], y[n + 1];
    FOR(i, 1, n + 1) {
        cin >> x[i] >> y[i];
    }

    vector<array<ll, 3>> a(n + 1);
    for(int i = 1; i <= n; ++i) {
        a[i] = {x[i], y[i], i};
    }

    ll left[n + 1] = {}, right[n + 1] = {};
    for(int i = 1; i <= n; ++i) {
        for(int j = i; j >= 1; --j) {
            if(abs(x[j] - x[i]) <= y[i] - y[j])
                left[i] = j;
            else
                break;
        }

        for(int j = i; j <= n; ++j) {
            if(abs(x[j] - x[i]) <= y[i] - y[j])
                right[i] = j;
            else
                break;
        }
    }

    sort(1 + all(a), [&](array<ll, 3> lhs, array<ll, 3> rhs) {
        return lhs[1] > rhs[1];
            });

    ll ans = 0;
    BIT bit(n + 5);
    for(int i = 1; i <= n; ++i) {
        if(bit.get(a[i][2])) continue;
        ++ans;
        bit.add(1, left[a[i][2]]);
        bit.add(-1, right[a[i][2]] + 1);
    }

    cout << ans << nl;
}

signed main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    ll t = 1;
    // cin >> t;
    while (t--)
    {
        solve();
    }
}

• Subtask 1: 0 / 4
• Subtask 2: 7 / 7
• Subtask 3: 12 / 12
• Subtask 4: 21 / 21
• Subtask 5: 26 / 26
• Subtask 6: 0 / 10
• Subtask 7: 0 / 20