Submission #914663

#	Time	Username	Problem	Language	Result	Execution time	Memory
914663		NoLove	Balloons (CEOI11_bal)	C++14	100 / 100	162 ms	9828 KiB

bal

/**
 *    author : Lăng Trọng Đạt
 *    created: 22-01-2024 
**/
#include <bits/stdc++.h>
using namespace std;
#ifndef LANG_DAT
#define db(...) ;
#endif // LANG_DAT
#define int long long
#define mp make_pair
#define f first
#define se second
#define pb push_back
#define all(v) (v).begin(), (v).end()
using pii = pair<int, int>;
using vi = vector<int>;
#define FOR(i, a, b) for (int (i) = a; (i) <= (b); i++)
void mx(int& a, int b) { if (b > a) a = b; }
void mi(int& a, int b) { if (b < a) a = b; }
#define si(x) (int)(x.size())
const int INF = 1e18;
const int MOD = 1e9 + 7;

const int MAXN = 2e5 + 5;
int x[MAXN];
const double EPS = 1e-7;
double r[MAXN]; // r[i]: final radius of balloon i
int n;

double mx_radius(int i, int j) {
    if (i == 0) return INF;
    return (double)(x[i] - x[j])*(x[i] - x[j]) / 4. / r[i];
}

int32_t main() {
    cin.tie(0)->sync_with_stdio(0);
    if (fopen("hi.inp", "r")) {
        freopen("hi.inp", "r", stdin);
//        freopen("hi.out", "w", stdout);
    } 

    vi s = {0};
    r[0] = INF;
    x[0] = -1e8;
    cin >> n;
    int cnt = 0;
    FOR(i, 1, n) {
        cin >> x[i] >> r[i];
        // do {
        //     if (r[i] >= r[s.back()])
        //         s.pop_back();
        //     r[i] = min(r[i], mx_radius(s.back(), i));
        // } while (r[i] >= r)
        while (r[i] - mx_radius(s.back(), i) > EPS or r[i] - r[s.back()] > EPS) {
            db(s, r[i], r[s.back()])
            r[i] = min(r[i], mx_radius(s.back(), i));

            if (r[i] - r[s.back()] > EPS)
                s.pop_back();
            else break;
            // db(i, s, r[i], r[s.back()])
            // db(i, mx_radius(s.back(), i) < r[i], r[i] - mx_radius(s.back(), i) < EPS)
        }
        s.push_back(i);
        cout << fixed << setprecision(4) << r[i] << "\n";
    }
    db(cnt)
}

Compilation message (stderr)

bal.cpp: In function 'int32_t main()':
bal.cpp:18:31: warning: unnecessary parentheses in declaration of 'i' [-Wparentheses]
   18 | #define FOR(i, a, b) for (int (i) = a; (i) <= (b); i++)
      |                               ^
bal.cpp:48:5: note: in expansion of macro 'FOR'
   48 |     FOR(i, 1, n) {
      |     ^~~
bal.cpp:47:9: warning: unused variable 'cnt' [-Wunused-variable]
   47 |     int cnt = 0;
      |         ^~~
bal.cpp:39:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   39 |         freopen("hi.inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 10 / 10
• Subtask 4: 10 / 10
• Subtask 5: 10 / 10
• Subtask 6: 10 / 10
• Subtask 7: 10 / 10
• Subtask 8: 10 / 10
• Subtask 9: 10 / 10
• Subtask 10: 10 / 10