Submission #1122137

#	Time	Username	Problem	Language	Result	Execution time	Memory
1122137		Requiem	Hacker (BOI15_hac)	C++17	100 / 100	228 ms	59724 KiB

hac

#include<bits/stdc++.h>
#define int long long
#define pb push_back
#define fast ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
#define MOD 1000000007
#define inf 1e18
#define fi first
#define se second
#define FOR(i,a,b) for(int i=a;i<=b;i++)
#define FORD(i,a,b) for(int i=a;i>=b;i--)
#define sz(a) ((int)(a).size())
#define endl '\n'
#define pi 3.14159265359
#define TASKNAME "hack"
using namespace std;
template<typename T> bool maximize(T &res, const T &val) { if (res < val){ res = val; return true; }; return false; }
template<typename T> bool minimize(T &res, const T &val) { if (res > val){ res = val; return true; }; return false; }
typedef pair<int,int> ii;
typedef pair<int,ii> iii;
typedef vector<int> vi;
const int MAXN = 2e6 + 9;
/**
1 vong tron tim cach choi sao cho duoc nhieu diem nhat.

1 tactic khi choi la dp. Nhung ma, lieu co cach nao ngoai dp ko.

Tập đỉnh mà mình hack được và tập đỉnh mà họ hack được sẽ phải là n / 2.

Với mỗi thằng mình sẽ muồn tìm cái sliding windown nhỏ nhất mà chứa nó thì kết quả sẽ là cái sliding đấy.
**/

int a[MAXN], pre[MAXN], answer[MAXN];
int n;

int getRange(int l, int r){
    return pre[r] - pre[l - 1];
}

struct segmentTree{
    struct Node{
        int mn = inf;
    };

    vector<Node> st;

    segmentTree(int sz = 0){
        st.resize(sz * 4 + 9);
    }

    void getPos(int nn, int l, int r, int pos, int &ans){
        minimize(ans, st[nn].mn);
        if (l == r){
            return;
        }

        int mid = (l + r) >> 1;
        if (pos <= mid) getPos(nn << 1, l, mid, pos, ans);
        else getPos(nn << 1 | 1, mid + 1, r, pos, ans);
    }
    void changeMin(int nn, int l, int r, int u, int v, int x){

        if (l >= u and r <= v) {
            minimize(st[nn].mn, x);
            return;
        }

        if (l > v or r < u) return;

        int mid = (l + r) >> 1;
        changeMin(nn << 1, l, mid, u, v, x);
        changeMin(nn << 1 | 1, mid + 1, r, u, v, x);
    }
};
main()
{
    fast;
    if (fopen(TASKNAME".inp","r")){
        freopen(TASKNAME".inp","r",stdin);
        freopen(TASKNAME".out","w",stdout);
    }
    cin>>n;
    segmentTree opt(n + 1);
    FOR(i, 1, n){
        cin >> a[i];
        a[i + n] = a[i];
        a[i + 2 * n] = a[i];
    }
    FOR(i, 1, 3 * n){
        pre[i] = pre[i - 1] + a[i];
    }

    memset(answer, 0x3f,sizeof(answer));
    int ans = 0;
    int taken = n / 2 + (n&1);

    int sum = 0;

    FOR(i, taken, 3 * n){
        int sum = pre[i] - pre[i - taken];

        int l = (i - taken + 1) % n + 1;
        int r = i % n + 1;

        if (l > r) {
            opt.changeMin(1, 1, n, l, n, sum);
            opt.changeMin(1, 1, n, 1, r, sum);
        }
        else{
            opt.changeMin(1, 1, n, l, r, sum);
        }
//        FOR(j, i - taken + 1, i){
//
//            minimize(answer[j % n + 1], sum);
//        }
    }

    FOR(i, 1, n){
        int res = inf;
        opt.getPos(1, 1, n, i, res);
        maximize(ans, res);
    }
    cout << ans << endl;





}
/**
Warning:
Đọc sai đề???
Cận lmao
Code imple thiếu case nào không.
Limit.
**/

Compilation message (stderr)

hac.cpp:74:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   74 | main()
      | ^~~~
hac.cpp: In function 'int main()':
hac.cpp:96:9: warning: unused variable 'sum' [-Wunused-variable]
   96 |     int sum = 0;
      |         ^~~
hac.cpp:78:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   78 |         freopen(TASKNAME".inp","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
hac.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(TASKNAME".out","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 20 / 20
• Subtask 2: 20 / 20
• Subtask 3: 20 / 20
• Subtask 4: 40 / 40