Submission #1212393

#	Time	Username	Problem	Language	Result	Execution time	Memory
1212393		nmhung	Feast (NOI19_feast)	C++20	100 / 100	108 ms	11008 KiB

feast

#include <bits/stdc++.h>

using namespace std;

mt19937_64 rd(chrono::steady_clock::now().time_since_epoch().count());

#define TIME (1.0 * clock() / CLOCKS_PER_SEC)
#define rf if(fopen(name".inp", "r")) {freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout);}
//#define in ({int x = 0; int c = getchar(), n = 0; for(; !isdigit(c); c = getchar()) n = (c == '-'); for(; isdigit(c); c = getchar()) x = x * 10 + c - '0'; n ? -x : x;})

#define bit(i, mask) (((mask) >> (i)) & 1)
#define on(i, mask) ((mask) | (1LL << (i)))
#define off(i, mask) ((mask) & (~(1LL << (i))))

#define ll long long
#define fi first
#define se second
#define pii pair<int, int>
#define plx pair<ll, int>
#define vi vector<int>
#define vvi vector<vi>
#define all(a) (a).begin(), (a).end()
#define len(x) ((int)(x).size())
#define pb push_back
#define endl '\n'
#define ub(x, i) upper_bound(all(x), i) - x.begin()
#define lb(x, i) lower_bound(all(x), i) - x.begin()

#define name "feast"

template<typename T1, typename T2> bool mini(T1 &a, T2 b)
    {if(a > b) a = b; else return 0; return 1;}
template<typename T1, typename T2> bool maxi(T1 &a, T2 b)
    {if(a < b) a = b; else return 0; return 1;}

const int mod = 1e9+7;
const int inf = 1e9+9;
const ll oo = 1e18l+7;
const int M = 5e5+6;
const int N = 3e5+6;
const int LOG = 31 - __builtin_clz(N);

int n, k, a[N];
pair<ll, int> dp[N][2];

void inp(){
    cin >> n >> k;
    for(int i = 1; i <= n; i++) cin >> a[i];
}

pair<ll, int> calc(ll lmb){
    dp[1][0] = {0, 0};
    dp[1][1] = {a[1] - lmb, 1};

    for(int i = 2; i <= n; i++){
        dp[i][0] = max(dp[i - 1][0], dp[i - 1][1]);
        dp[i][1] = max(make_pair(dp[i - 1][1].fi + a[i], dp[i - 1][1].se),
                       make_pair(dp[i - 1][0].fi + a[i] - lmb, dp[i - 1][0].se + 1));
    }
    return max(dp[n][0], dp[n][1]);
}

void proc(){
    ll l = 0, r = 1e18, lmb = 0;
    while(l <= r){
        ll mid = (l + r) >> 1;
        pair<ll, int> tmp = calc(mid);
        if(tmp.se >= k){
            lmb = mid;
            l = mid + 1;
        }
        else r = mid - 1;
    }
    cout << calc(lmb).fi + lmb * k;
}

int main(){
    cin.tie(nullptr)->sync_with_stdio(false);

    rf

    int test = 1;
    //cin >> test;

    while(test--){
        inp();
        proc();
    }

    cerr << "Time elapsed: " << TIME << "s" << endl;
    return 0;
}

Compilation message (stderr)

feast.cpp: In function 'int main()':
feast.cpp:8:47: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    8 | #define rf if(fopen(name".inp", "r")) {freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout);}
      |                                        ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
feast.cpp:80:5: note: in expansion of macro 'rf'
   80 |     rf
      |     ^~
feast.cpp:8:80: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    8 | #define rf if(fopen(name".inp", "r")) {freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout);}
      |                                                                         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
feast.cpp:80:5: note: in expansion of macro 'rf'
   80 |     rf
      |     ^~

• Subtask 1: 4 / 4
• Subtask 2: 8 / 8
• Subtask 3: 18 / 18
• Subtask 4: 10 / 10
• Subtask 5: 11 / 11
• Subtask 6: 20 / 20
• Subtask 7: 29 / 29