Submission #1165638

#	Time	Username	Problem	Language	Result	Execution time	Memory
1165638		spycoderyt	Feast (NOI19_feast)	C++20	100 / 100	189 ms	12148 KiB

feast

#include <bits/stdc++.h>
#define f first
#define s second
#define int long long
using namespace std;
/*
instead of enforcing K, we find the lambda that produces K, then just do cost + lambda * K

*/
const int N = 3e5+5;
int a[N];
int32_t main() {
    int n,k;
    cin >> n >> k;
    for(int i = 0;i<n;i++)cin>>a[i];
    auto fc = [&](int lmb) {
        pair<int,int> dp[n][2];
        dp[0][0] = {0,0};
        dp[0][1] = {a[0] - lmb,1};
        for(int i = 1;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].f + a[i],dp[i-1][1].s),
                make_pair(dp[i-1][0].f + a[i] - lmb,dp[i-1][0].s + 1)
            );
        }
        return max(dp[n-1][0],dp[n-1][1]);
    };
    int lo = 0, hi = 1e17;
    while(lo<hi){
        int mid = (lo + 1 + hi)/2;
        fc(mid).s >= k ? lo = mid : hi = mid-1;
    }
    cout << fc(lo).f + lo * k;
}
/*
cost UP, k down
if k too high, then cost up (lo = mid)
if k too low, then cost down (hi = mid-1)
*/

• 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