Submission #831746

#	Time	Username	Problem	Language	Result	Execution time	Memory
831746		maomao90	Seesaw (JOI22_seesaw)	C++17	100 / 100	53 ms	12936 KiB

seesaw

// Hallelujah, praise the one who set me free
// Hallelujah, death has lost its grip on me
// You have broken every chain, There's salvation in your name
// Jesus Christ, my living hope
#include <bits/stdc++.h> 
using namespace std;

#define REP(i, s, e) for (int i = (s); i < (e); i++)
#define RREP(i, s, e) for (int i = (s); i >= (e); i--)
template <class T>
inline bool mnto(T& a, T b) {return a > b ? a = b, 1 : 0;}
template <class T>
inline bool mxto(T& a, T b) {return a < b ? a = b, 1: 0;}

typedef unsigned long long ull;
typedef long long ll;
typedef long double ld;
#define FI first
#define SE second
typedef pair<int, int> ii;
typedef pair<ll, ll> pll;
typedef tuple<int, int, int> iii;
#define ALL(_a) _a.begin(), _a.end()
#define SZ(_a) (int) _a.size()
#define pb push_back
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<ii> vii;
typedef vector<iii> viii;

#ifndef DEBUG
#define cerr if (0) cerr
#endif

const int INF = 1000000005;
const ll LINF = 1000000000000000005ll;
const int MAXN = 200005;

int n;
int a[MAXN];
ll psm[MAXN];
ld ans;

int main() {
#ifndef DEBUG
    ios::sync_with_stdio(0), cin.tie(0);
#endif
    cin >> n;
    REP (i, 1, n + 1) {
        cin >> a[i];
        psm[i] = a[i] + psm[i - 1];
    }
    int l = 1, r = n;
    ld mx = (ld) psm[r] / n;
    vector<tuple<ld, int, int>> cand;
    REP (z, 0, n) {
        ld lsm = (ld) (psm[r] - psm[l]) / (r - l),
           rsm = (ld) (psm[r - 1] - psm[l - 1]) / (r - l);
        if (lsm <= mx) {
            cand.pb({lsm, ++l, r});
        } else {
            cand.pb({rsm, l, --r});
        }
    }
    sort(ALL(cand));
    ans = LINF;
    for (auto [mn, l, r] : cand) {
        mnto(ans, mx - mn);
        mxto(mx, (ld) (psm[r + 1] - psm[l]) / (r - l + 1));
    }
    cout << setprecision(15) << ans << '\n';
    return 0;
}

• Subtask 1: 1 / 1
• Subtask 2: 33 / 33
• Subtask 3: 33 / 33
• Subtask 4: 33 / 33