Submission #527128

#	Time	Username	Problem	Language	Result	Execution time	Memory
527128		jalsol	Bigger segments (IZhO19_segments)	C++11	100 / 100	89 ms	14920 KiB

segments

#include <bits/stdc++.h>

using namespace std;

#define Task ""

struct __Init__ {
    __Init__() {
        cin.tie(nullptr)->sync_with_stdio(false);
        if (fopen(Task".inp", "r")) {
            freopen(Task".inp", "r", stdin);
            freopen(Task".out", "w", stdout); }
    }
} __init__;

using ll = long long;

#ifdef LOCAL
#define debug(x) cerr << "[" #x " = " << x << "]\n";
#else
#define debug(...)
#endif // LOCAL

#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define fi first
#define se second

#define For(i, l, r) for (int i = (l); i <= (r); ++i)
#define Ford(i, r, l) for (int i = (r); i >= (l); --i)
#define Rep(i, n) For (i, 0, (n) - 1)
#define Repd(i, n) Ford (i, (n) - 1, 0)

template<class C> int isz(const C& c) { return c.size(); }
template<class T> bool chmin(T& a, const T& b) { if (a > b) { a = b; return true; } return false; }
template<class T> bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } return false; }

constexpr int eps = 1e-9;
constexpr int inf = 1e9;
constexpr ll linf = 1e18;

// =============================================================================

constexpr int maxN = 5e5 + 5;

int n;
int a[maxN];

ll pref[maxN];
int pos[maxN];
int dp[maxN];

signed main() {
    cin >> n;
    For (i, 1, n) cin >> a[i];

    For (i, 1, n) {
        pref[i] = pref[i - 1] + a[i];
    }

    For (i, 1, n) {
        chmax(pos[i], pos[i - 1]);
        dp[i] = dp[pos[i]] + 1;

        ll sum = 2 * pref[i] - pref[pos[i]];
        int p = lower_bound(pref + 1, pref + n + 1, sum) - pref;
        chmax(pos[p], i);
    }

    cout << dp[n] << '\n';
}

/*
    pref[i] - pref[j] >= pref[j] - pref[k]
    pref[i] >= 2 * pref[j] - pref[k]
*/

Compilation message (stderr)

segments.cpp: In constructor '__Init__::__Init__()':
segments.cpp:11:20: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   11 |             freopen(Task".inp", "r", stdin);
      |             ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
segments.cpp:12:20: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   12 |             freopen(Task".out", "w", stdout); }
      |             ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 13 / 13
• Subtask 2: 14 / 14
• Subtask 3: 10 / 10
• Subtask 4: 36 / 36
• Subtask 5: 27 / 27