Submission #3237655

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Source Code Expand

#include <cmath>
#include <algorithm>
#include <iostream>
using namespace std;
int main() {
    int n; cin >> n;
    long long a[n], ans = 1LL<<60;
    for (int i = 0; i < n; i++) { cin >> a[i]; if (i > 0) a[i] += a[i-1]; }
    for (int i = 1; i < n-2; i++) {
        long long p, q, r, s;
        int j = lower_bound(a, a + i + 1, (a[i]+1)/2) - a;
        if (j == 0) { p = a[0]; q = a[i] - a[0]; }
        else if (j == i) { p = a[i-1]; q = a[i] - a[i-1]; }
        else if (abs(a[i] - 2 * a[j-1]) > abs(a[i] - 2 * a[j])) {
            p = a[j]; q = a[i] - a[j];
        } else { p = a[j-1]; q = a[i] - a[j-1]; }
        int k = lower_bound(a + i + 1, a + n, (a[n-1]+a[i]+1)/2) - a;
        if (k == i + 1) { r = a[i+1] - a[i]; s = a[n-1] - a[i+1]; }
        else if (k == n-1) { r = a[n-2] - a[i]; s = a[n-1] - a[n-2]; }
        else if (abs(a[n-1] + a[i] - 2* a[k-1]) > abs(a[n-1] + a[i] - 2 * a[k])) {
            r = a[k] - a[i]; s = a[n-1] - a[k];
        } else { r = a[k-1] - a[i]; s = a[n-1] - a[k-1]; }
        // cout << j << ' ' << i << ' ' << k << "; " << p << ' ' << q << ' ' << r << ' ' << s << endl;
        ans = min(ans, max({p, q, r, s}) - min({p, q, r, s}));
    }
    cout << ans << endl;
}

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