Submission #909407

#	Time	Username	Problem	Language	Result	Execution time	Memory
909407		LOLOLO	Lightning Rod (NOI18_lightningrod)	C++17	0 / 100	1253 ms	262144 KiB

Main

#include <bits/stdc++.h>
#define fi first
#define se second
using namespace std;

typedef long long ll;
typedef pair<ll, ll> pa;

const ll N = 1e6 + 1;
const ll MOD = 1e9 + 7;
const ll INF = 1e12;
int pr[N], suff[N];

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int n;
    cin >> n;

    vector <pair <int, int>> v;
    for (int i = 1; i <= n; i++) {
        int x, y;
        cin >> x >> y;
        v.push_back({x, y});
    }

    pr[0] = v[0].fi - v[0].se;
    for (int i = 1; i < n; i++) {
        pr[i] = max(pr[i - 1], v[i].fi + v[i].se);
    }

    suff[n - 1] = v[n - 1].fi + v[n - 1].se;
    for (int i = n - 2; i >= 0; i--) {
        suff[i] = min(suff[i + 1], v[i].fi - v[i].se);
    }

    int cnt = 0;
    if (suff[1] > v[0].fi - v[0].se)
        cnt++;

    if (pr[n - 2] < v[n - 1].fi + v[n - 1].se)
        cnt++;

    for (int i = 1; i < n - 1; i++) {
        if (suff[i + 1] > v[i].fi - v[i].se && pr[i - 1] < v[i].fi + v[i].se) {
            cnt++;
        }
    }

    cout << cnt << '\n';
    return 0;
}

// x(i) - x(j) <= y(i) - y(j)
// x(i) - y(i) <= x(j) - y(j)

// x(j) - x(i) <= y(i) - y(j)
// x(j) + y(j) <= x(i) + y(i)

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