Submission #1212390

#	Time	Username	Problem	Language	Result	Execution time	Memory
1212390		huudai	Feast (NOI19_feast)	C++20	18 / 100	88 ms	10832 KiB

feast

#include <bits/stdc++.h>

using namespace std;

#define ll long long
#define fi first
#define se second
#define pii pair<int, int>
#define pll pair<ll,ll>
#define mp make_pair
#define pb push_back

#define BIT(x,i) (((x)>>(i))&1)
#define MASK(i) (1LL<<(i))  

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

#define file "task"

const int maxn = 3e5 + 5;
const int MOD  = 1e9 + 7;
const int oo   = 1e9;
const ll  OO   = 1e18;

int n;
int k;
int a[maxn];
pll f[maxn][2];

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

void dp(ll m){
    memset(f, -0x3f, sizeof(f));
    f[0][0] = mp(0, 0);
    for(int i = 0; i < n; i++){
        maximize(f[i + 1][0], max(f[i][0], f[i][1]));
        maximize(f[i + 1][1], mp(f[i][0].fi + a[i + 1] - m, f[i][0].se + 1));
        maximize(f[i + 1][1], mp(f[i][1].fi + a[i + 1], f[i][1].se));
    }
}

void proc(){
    ll l = 0, r = (ll)1e15;
    ll ans = 0;
    while(l <= r){
        ll m = (l + r) >> 1;
        dp(m);
        pll check = max(f[n][0], f[n][1]);

        if(check.se >= k){
            ans = check.fi + 1LL * k * m;
            l = m + 1;
        } else r = m - 1;
    }

    cout << ans;
}
signed main(){
    cin.tie(nullptr)->sync_with_stdio(0); cout.tie(nullptr);    
    if(fopen(file".inp", "r")){
        freopen(file".inp", "r", stdin);
        freopen(file".out", "w", stdout);
    }
    
    input();
    proc();

    return 0;
}

Compilation message (stderr)

feast.cpp: In function 'int main()':
feast.cpp:67:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   67 |         freopen(file".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
feast.cpp:68:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   68 |         freopen(file".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 4
• Subtask 2: 0 / 8
• Subtask 3: 18 / 18
• Subtask 4: 0 / 10
• Subtask 5: 0 / 11
• Subtask 6: 0 / 20
• Subtask 7: 0 / 29