Submission #1122738

#	Time	Username	Problem	Language	Result	Execution time	Memory
1122738		gdragon	Bigger segments (IZhO19_segments)	C++20	0 / 100	1 ms	320 KiB

segments

#include <bits/stdc++.h>
using namespace std;
#define TASK "long"
#define fi first
#define se second
#define ll long long
#define pb push_back
#define ALL(x) (x).begin(), (x).end()
#define GETBIT(mask, i) ((mask) >> (i) & 1)
#define MASK(i) ((1LL) << (i))
#define SZ(x) ((int)(x).size())
#define mp make_pair
#define CNTBIT(mask) __builtin_popcount(mask)
template<class X, class Y> bool maximize(X &x, Y y){ if (x < y) {x = y; return true;} return false;};
template<class X, class Y> bool minimize(X &x, Y y){ if (x > y) {x = y; return true;} return false;};
typedef pair<int, int> ii;
const int N = 5e5 + 5;
const int inf = 1e9 + 7;
const long long INF = (long long)1e18 + 7;
const int mod = 1e9 + 7;
void add(int &x, int y) {x += y; if (x >= mod) x -= mod;}
void sub(int &x, int y) {x -= y; if (x < 0) x += mod;}
int mul(int x, int y) {return 1LL * x * y % mod;}
// -----------------------------------------//
struct Fenwick {
    int n;
    vector<long long> v;
    Fenwick(int _n = 0) {
        n = _n;
        v.assign(n + 2, INF);
    }
    void update(int x, long long c) {
        for(; x > 0; x -= x & -x) v[x] = min(v[x], c);
    } 
    long long getMin(int x) {
        long long ans = INF;
        for(; x <= n; x += x & -x) ans = min(ans, v[x]);
        return ans;
    }
} fw;
int n;
int a[N], dp[N];
long long pref[N], f[N];
void read() {
    cin >> n;
    for(int i = 1; i <= n; i++) cin >> a[i];
}
void solve() {
    for(int i = 1; i <= n; i++) pref[i] = pref[i - 1] + a[i]; 
    fw = Fenwick(n);
    dp[1] = 1;
    f[1] = pref[1] + a[1];
    fw.update(1, f[1]);
    for(int i = 2; i <= n; i++) {
        int l = 1, r = i - 1, ans = -1;
        while(l <= r) {
            int mid = (l + r) >> 1;
            if (fw.getMin(mid) <= pref[i]) {
                ans = mid;
                l = mid + 1;
            }
            else r = mid - 1;
        }
        if (ans == -1) {
            dp[i] = dp[i - 1];
            f[i] = f[i - 1] + a[i];
        }
        else {
            dp[i] = dp[ans] + 1;
            f[i] = pref[i] - pref[ans];
        }
        fw.update(i, f[i]);
    }
    cout << dp[n];
}
signed main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    if (fopen(TASK".inp", "r")) {
        freopen(TASK".inp", "r", stdin);
        freopen(TASK".out", "w", stdout);
    }
    int test = 1;
    // cin >> test;
    while(test--) {
        read();
        solve();
    }
    return 0;
}

Compilation message (stderr)

segments.cpp: In function 'int main()':
segments.cpp:79:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   79 |         freopen(TASK".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
segments.cpp:80:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   80 |         freopen(TASK".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 13
• Subtask 2: 0 / 14
• Subtask 3: 0 / 10
• Subtask 4: 0 / 36
• Subtask 5: 0 / 27