Submission #705546

#	Time	Username	Problem	Language	Result	Execution time	Memory
705546		dooompy	Sparklers (JOI17_sparklers)	C++17	100 / 100	570 ms	7032 KiB

sparklers

#include "bits/stdc++.h"

using namespace std;

void abc() {cout << endl;}
template <typename T, typename ...U> void abc(T a, U ...b) {
    cout << a << ' ', abc(b...);
}
template <typename T> void printv(T l, T r) {
    while (l != r) cout << *l << " \n"[++l == r];
}
template <typename A, typename B> istream& operator >> (istream& o, pair<A, B> &a) {
    return o >> a.first >> a.second;
}
template <typename A, typename B> ostream& operator << (ostream& o, pair<A, B> a) {
    return o << '(' << a.first << ", " << a.second << ')';
}
template <typename T> ostream& operator << (ostream& o, vector<T> a) {
    bool is = false;
    for (T i : a) {o << (is ? ' ' : '{'), is = true, o << i;}
    return o << '}';
}

#ifdef local
#define test(args...) abc("[" + string(#args) + "]", args)
#else
#define test(args...) void(0)
#endif

using ll = long long;

#define int ll

int a[100005];

struct node {
    ll mn, mx;
};

node tree[4 * 100005];
int ans = 2e9;

void comb(int x) {
    tree[x].mn = min(tree[2 * x].mn, tree[2 * x + 1].mn);
    tree[x].mx = max(tree[2 * x].mx, tree[2 * x + 1].mx);
}

void sett(int x, int l, int r, int p, ll v) {
    if (l == r) {
        tree[x].mn = tree[x].mx = v;
        return;
    }

    int mid = (l + r) / 2;

    if (p <= mid) sett(2 * x, l, mid, p, v);
    else sett(2 * x + 1, mid + 1, r, p, v);

    comb(x);
}

int n, k, t;
int x[100005];

int bigger(int x, int l, int r, int ql, int qr, int v) {
    if (ql <= l && r <= qr) {
        if (tree[x].mx >= v) {
            if (l == r) return l;
            int mid = (l + r) / 2;
            if (tree[2 * x].mx >= v) return bigger(2 * x, l, mid, ql, qr, v);
            else return bigger(2 * x + 1, mid + 1, r, ql, qr, v);
        } else {
            return -1;
        }
    }

    if (ql > r || l > qr) return -1;

    int mid = (l + r) / 2;
    int res = bigger(2 * x, l, mid, ql, qr, v);
    if (res == -1) res = bigger(2 * x + 1, mid + 1, r, ql, qr, v);
    return res;
}

int smaller(int x, int l, int r, int ql, int qr, int v) {
    if (ql <= l && r <= qr) {
        if (tree[x].mn <= v) {
            if (l == r) return l;
            int mid = (l + r) / 2;
            if (tree[2 * x + 1].mn <= v) return smaller(2 * x + 1, mid + 1, r, ql, qr, v);
            else return smaller(2 * x, l, mid, ql, qr, v);
        } else {
            return -1;
        }
    }

    if (ql > r || l > qr) return -1;

    int mid = (l + r) / 2;
    int res = smaller(2 * x + 1, mid + 1, r, ql, qr, v);
    if (res == -1) return smaller(2 * x, l, mid, ql, qr, v);
    return res;
}

bool check(int s) {
    int dist = s * t * 2; // in one sec

    for (int i = 1; i <= n; i++) {
        x[i] = a[i] - dist * i;
        sett(1, 1, n + 1, i, x[i]);
    }

    int tochange = bigger(1, 1, n + 1, k, n + 1, x[k] + 1) - 1;

    for (int i = k - 1; i >= 1; i--) {
        if (x[i + 1] <= x[i]) {
            // dont need help

            tochange = bigger(1, 1, n + 1, tochange, n + 1, x[i] + 1) - 1;
        } else {
            tochange = smaller(1, 1, n + 1, k, tochange, x[i]);
            if (tochange == -1) return false;
        }
    }

    return (tochange == n);
}

signed main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
//    freopen("", "r", stdin);
//    freopen("", "w", stdout);
    cin >> n >> k >> t;
    for (int i = 1; i <= n; i++) cin >> a[i];
    a[n + 1] = a[n];
    sett(1, 1, n + 1, n + 1, 1e18);

    int lo = 0, hi = 1e10;

    while (lo <= hi) {
        int mid = (lo + hi) / 2;
        if (check(mid)) {
            ans = min(ans, mid);
            hi = mid - 1;
        } else lo = mid + 1;
    }

    cout << ans;
}

• Subtask 1: 30 / 30
• Subtask 2: 20 / 20
• Subtask 3: 50 / 50