Submission #853919

#	Time	Username	Problem	Language	Result	Execution time	Memory
853919		annabeth9680	Discharging (NOI20_discharging)	C++17	100 / 100	98 ms	29008 KiB

Discharging

#include <bits/stdc++.h>
#define int long long
using namespace std;
const int MAXN = 1e6+11;
int arr[MAXN], dp[MAXN], A[MAXN], B[MAXN];
int L,R;
int teil(int a, int b){
    return a/b-(a % b != 0 && a < 0);
}
int steigung(int a1, int b1, int a2, int b2){
    return teil(b2-b1,a1-a2);
}
void upd(int i, int x){
    while(R-L >= 2 && steigung(A[R-2],B[R-2],i,x) <= steigung(A[R-2],B[R-2],A[R-1],B[R-1])) R--;
    A[R] = i; B[R] = x; R++;
}
int query(int x){
    while(R-L >= 2 && A[L]*x+B[L] >= A[L+1]*x+B[L+1]) L++;
	return A[L]*x+B[L];
}
int32_t main()
{
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    int N; cin >> N;
    for(int i = 0;i<N;++i) cin >> arr[i];
    for(int i = 1;i<N;++i) arr[i] = max(arr[i],arr[i-1]);
    memset(dp,0x3f,sizeof(dp)); dp[0] = 0;
    for(int i = 0;i<N;++i){
        upd(-i, dp[i]);
        dp[i+1] = arr[i]*N+query(arr[i]);
    }
    cout << dp[N] << "\n";
    return 0;
}

• Subtask 1: 9 / 9
• Subtask 2: 13 / 13
• Subtask 3: 25 / 25
• Subtask 4: 11 / 11
• Subtask 5: 14 / 14
• Subtask 6: 28 / 28