Submission #628046

#	Time	Username	Problem	Language	Result	Execution time	Memory
628046		vbee	Bigger segments (IZhO19_segments)	C++14	100 / 100	167 ms	34544 KiB

segments

#include <bits/stdc++.h>
#define fi first
#define se second
#define TASK "simpsegments"
#define pb push_back
#define all(r) (r).begin(), (r).end()
#define ll long long
#define MASK(i) (1 << (i))
#define BIT(x, i) ((x) >> (i) & 1)

using namespace std;

const int LOG = 19;
const int oo = 1e9 + 7;
const ll loo = (ll)1e18 + 7;
const int N = 5e5 + 7;

int n, trace[N];
ll f[N], pre[N], a[N];

bool minimize(ll &a, ll b){
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}

struct segtree{
    vector<ll> t;
    segtree(int _n){
        t.resize(4 * _n + 7);
        for (int i = 1; i < 4 * _n; i++) t[i] = loo;
    }
    void update(int v, int lt, int rt, int pos, ll value){
        if (lt == rt) return (void)(t[v] = value);
        int middle = (rt + lt) / 2;
        if (pos <= middle) update(v * 2, lt, middle, pos, value);
        else update(v * 2 + 1, middle + 1, rt, pos, value);
        t[v] = min(t[v * 2], t[v * 2 + 1]);
    }

    int getid(int v, int lt, int rt, ll value){
        if (t[v] > value) return -1;
        if (lt == rt) return lt;
        int middle = (rt + lt) / 2;
        int temp = getid(v * 2 + 1, middle + 1, rt, value);
        if (temp == -1) return getid(v * 2, lt, middle, value);
        else return temp;
    }
};
int main(){
    ios_base::sync_with_stdio(0); cin.tie(0);
//    freopen(TASK".inp", "r", stdin);
//    freopen(TASK".out", "w", stdout);
    cin >> n;
    for (int i = 1; i <= n; i++) cin >> a[i];
    for (int i = 1; i <= n; i++) pre[i] = pre[i - 1] + a[i];

    for (int i = 1; i <= n; i++) f[i] = loo;
    segtree seg(n + 1);
    seg.update(1, 1, n + 1, 1, 0);
    for (int i = 1; i <= n; i++){
        int cur = seg.getid(1, 1, n + 1, pre[i]);
        if (minimize(f[i], pre[i] - pre[cur - 1])) trace[i] = cur - 1;
        seg.update(1, 1, n + 1, i + 1, f[i] + pre[i]);
    }
    int cur = n, res = 0;
    while (cur != 0) {
        cur = trace[cur];
        res++;
    }
    cout << res;
//    }
    return 0;
}

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