Submission #1123796

#	Time	Username	Problem	Language	Result	Execution time	Memory
1123796		LTTrungCHL	Feast (NOI19_feast)	C++20	100 / 100	169 ms	12180 KiB

feast

///***LTT***///
/// ->NHAT QUOC GIA<- ///
#include<bits/stdc++.h>
//#pragma GCC optimize ("O3")
//#pragma GCC optimize ("unroll-loops")
//#pragma GCC target("popcnt")
//#define int long long
#define endl "\n"
#define F first
#define S second
#define pb push_back
using namespace std;
//vector <int> lg2;
//void LOG_ARR(int n){
//    lg2.resize(n + 3);
//    for (int i = 1;i <= n;++i){
//        lg2[i] = __lg(i);
//    }
//}
const long long oo = 1e9+7;
const int N = 3 * 1e5 + 10;
int n, k;
long long a[N];
pair <long long, int> dp[N][2];
pair <long long, int> gendp(long long lambda){
    for (int i = 1;i <= n;++i){
        for (int j = 0;j <= 1;++j){
            dp[i][j] = {0, 0};
        }
    }
    dp[1][1] = {a[1] - lambda,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][0].F - lambda + a[i], dp[i - 1][0].S + 1), make_pair(dp[i - 1][1].F + a[i], dp[i - 1][1].S) );
    }
    return max(dp[n][0], dp[n][1]);
}
void solve(){
    cin >> n >> k;
    for (int i = 1;i <= n;++i){
        cin >> a[i];
    }
    long long l = 0, r = 1e18;
    long long res = 0;
    while (l <= r){
        long long mid = (l + r)/2;
        if (gendp(mid).S >= k){
            l = mid + 1;
            res = mid;
        } else r = mid - 1;
    }
    pair <long long, int> ans = gendp(res);
//    cout << ans.F <<"\n";
    cout << ans.F + res * ans.S ;
    return;
}
int main(){
    ios_base::sync_with_stdio(NULL);
    cin.tie(NULL);
    cout.tie(NULL);
    if (fopen("npt.inp", "r")){
        freopen("npt.inp", "r", stdin);
        freopen("npt.out", "w", stdout);
    }
//    int t;
//    cin >> t;
//    while(t--){
    solve();
//    }
/////////
    return 0;
}

Compilation message (stderr)

feast.cpp: In function 'int main()':
feast.cpp:62:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   62 |         freopen("npt.inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
feast.cpp:63:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   63 |         freopen("npt.out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

• 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