Submission #41253

#	Time	Username	Problem	Language	Result	Execution time	Memory
41253		grumpy_gordon	Sparklers (JOI17_sparklers)	C++14	0 / 100	2 ms	632 KiB

sparklers

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#include <bits/stdc++.h>

//#pragma GCC optimize("O3")
//#pragma GCC optimize("Ofast,no-stack-protector")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx")
//#pragma GCC target("avx,tune=native")
//float __attribute__((aligned(32)))

using namespace std;

typedef long long ll;

typedef unsigned long long ull;

typedef long double ld;

int mysqrt(ll x){
    int l = 0, r = 1e9 + 1;
    while (r - l > 1){
        int m = (l + r) / 2;
        if (m * (ll)m <= x)
            l = m;
        else
            r = m;
    }
    return l;
}

mt19937 rnd(1337);

ll AR = 19, BR = 13, CR = 23, XR = 228, YR = 322, MODR = 1e9 + 993;

ll myrand(){
    ll ZR = (XR * AR + YR * BR + CR) % MODR;
    XR = YR;
    YR = ZR;
    return ZR;
}

const int Mod = 1e9 + 7;

int bpow(int x, int y){
    if (y == 0)
        return 1;
    if (y == 1)
        return x;
    int ret = bpow(x, y >> 1);
    ret = (ret * (ll)ret) % Mod;
    if (y & 1)
        ret = (ret * (ll)x) % Mod;
    return ret;
}

int bdiv(int x, int y){
    return (x * (ll)bpow(y, Mod - 2)) % Mod;
}

void setmin(int &x, int y){
    x = min(x, y);
}

void setmax(int &x, int y){
    x = max(x, y);
}

void setmin(ll &x, ll y){
    x = min(x, y);
}

void setmax(ll &x, ll y){
    x = max(x, y);
}

int gcd(int a, int b){
    return a ? gcd(b % a, a) : b;
}

const ll llinf = 2e18 + 100;

const double eps = 1e-9;

const int maxn = 1e5 + 100, maxw = 1e6 + 100, inf = 2e9 + 100, sq = 300, mod = 1e9 + 7, LG = 17;

int n, k, t;

int a[maxn];

ll q[4 * maxn];

void build(int v, int l, int r, vector<ll> &arr){
    if (l == r){
        q[v] = arr[l];
        return;
    }
    int m = (l + r) / 2;
    build(2 * v, l, m, arr);
    build(2 * v + 1, m + 1, r, arr);
    q[v] = max(q[2 * v], q[2 * v + 1]);
}

int get(int v, int tl, int tr, int l, int r, ll val){
    if (l > r || q[v] < val)
        return -1;
    if (tl == tr)
        return tl;
    int m = (tl + tr) / 2;
    int ret = get(2 * v + 1, m + 1, tr, max(l, m + 1), r, val);
    if (ret != -1)
        return ret;
    return get(2 * v, tl, m, l, min(r, m), val);
}

bool check(int S){
    vector<ll> A, B;
    A.push_back(0);
    for (int i = k - 1; i >= 0; i--)
        A.push_back(-a[i] + min((ll)inf, 2 * S * (ll)t));
    B.push_back(0);
    for (int i = k; i < n; i++)
        B.push_back(B.back() + -a[i] + min((ll)inf, 2 * S * (ll)t));
    build(1, 0, B.size() - 1, B);
    vector<ll> C(B.size());
    C[0] = 0;
    for (int i = 1; i < C.size(); i++)
        C[i] = min(C[i - 1], B[i]);
    int last = 0;
    int l, r;
    l = -1, r = C.size();
    while (r - l > 1){
        int m = (l + r) / 2;
        if (C[m] >= 0)
            l = m;
        else
            r = m;
    }
    last = l;
    ll sum = 0;
    for (int i = 1; i < A.size(); i++){
        int val = A[i];
        sum += val;
        if (val >= 0){
            l = last, r = C.size();
            while (r - l > 1){
                int m = (l + r) / 2;
                if (C[m] + sum >= 0)
                    l = m;
                else
                    r = m;
            }
            last = l;
        }
        else{
            last = get(1, 0, B.size() - 1, 0, last, -sum);
            if (last == -1)
                return 0;
        }
    }
    return last == B.size() - 1;
}

int main()
{
    #ifdef ONPC
    //ifstream cin("a.in");
    //ofstream cout("a.out");
    freopen("a.in", "r", stdin);
    freopen("a.out", "w", stdout);
    #else
    //ifstream cin("sprinklers.in");
    //ofstream cout("sprinklers.out");
    //freopen("road.in", "r", stdin);
    //freopen("road.out", "w", stdout);
    #endif // ONPC
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    cin >> n >> k >> t;
    k--;
    for (int i = 0; i < n; i++){
        cin >> a[i];
        if (i)
            a[i - 1] = a[i] - a[i - 1];
    }
    n--;
    int l = -1, r = (1e9 + (ll)2 * t - 1) / (2 * t);
    while (r - l > 1){
        int m = (l + r) / 2;
        if (check(m))
            r = m;
        else
            l = m;
    }
    cout << r;
}

Compilation message (stderr)

sparklers.cpp: In function 'bool check(int)':
sparklers.cpp:209:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 1; i < C.size(); i++)
                       ^
sparklers.cpp:223:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 1; i < A.size(); i++){
                       ^
sparklers.cpp:243:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     return last == B.size() - 1;
                 ^

• Subtask 1: 0 / 30
• Subtask 2: 0 / 20
• Subtask 3: 0 / 50