10441: USACO 2024 February Contest, Platinum Problem 2. Minimum Sum of Maximums
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Description
Bessie has $N$ ($2\le N\le 300$) tiles in a line with ugliness values
$a_1, a_2, \dots, a_N$ in that order ($1\le a_i\le 10^6$). $K$
($0\le K\le \min(N,6)$) of the tiles are stuck in place; specifically, those at
indices $x_1,\dots, x_K$ ($1\le x_1 < x_2<\dots< x_K\le N$).
Bessie wants to minimize the total ugliness of the tiles, which is defined as the sum of the maximum ugliness over every consecutive pair of tiles; that is, $\sum_{i=1}^{N-1}\max(a_i,a_{i+1})$. She is allowed to perform the following operation any number of times: choose two tiles, neither of which are stuck in place, and swap them.
Determine the minimum possible total ugliness Bessie can achieve if she performs operations optimally.
Input
The first line contains $N$ and $K$.
The next line contains $a_1,\dots,a_N$.
The next line contains the $K$ indices $x_1,\dots,x_K$.
Output
Output the minimum possible total ugliness.
Constraints
- Input 5: $K=0$
- Inputs 6-7: $K=1$
- Inputs 8-12: $N\le 50$
- Inputs 13-24: No additional constraints
Sample 1 Input
3 0
1 100 10
Sample 1 Output
110
Bessie can swap the second and third tiles so that $a=[1,10,100]$, achieving
total ugliness $\max(1,10)+\max(10,100)=110$. Alternatively, she could swap the
first and second tiles so that $a=[100,1,10]$, also achieving total ugliness
$\max(100,1)+\max(1,10)=110$.
Sample 2 Input
3 1
1 100 10
3
Sample 2 Output
110
Bessie could swap the first and second tiles so that $a=[100,1,10]$, achieving
total ugliness $\max(100,1)+\max(1,10)=110$.
Sample 3 Input
3 1
1 100 10
2
Sample 3 Output
200
The initial total ugliness of the tiles is $\max(1,100)+\max(100,10)=200$.
Bessie is only allowed to swap the first and third tiles, which does not allow
her to reduce the total ugliness.
4 2
1 3 2 4
2 3
9