codeforces#P1954D. Colored Balls
Colored Balls
Description
There are balls of $n$ different colors; the number of balls of the $i$-th color is $a_i$.
The balls can be combined into groups. Each group should contain at most $2$ balls, and no more than $1$ ball of each color.
Consider all $2^n$ sets of colors. For a set of colors, let's denote its value as the minimum number of groups the balls of those colors can be distributed into. For example, if there are three colors with $3$, $1$ and $7$ balls respectively, they can be combined into $7$ groups (and not less than $7$), so the value of that set of colors is $7$.
Your task is to calculate the sum of values over all $2^n$ possible sets of colors. Since the answer may be too large, print it modulo $998\,244\,353$.
The first line contains a single integer $n$ ($1 \le n \le 5000$) — the number of colors.
The second line contains $n$ integers $a_1, a_2, \dots, a_n$ ($1 \le a_i \le 5000$) — the number of balls of the $i$-th color.
Additional constraint on input: the total number of balls doesn't exceed $5000$.
Print a single integer — the sum of values of all $2^n$ sets of colors, taken modulo $998\,244\,353$.
Input
The first line contains a single integer $n$ ($1 \le n \le 5000$) — the number of colors.
The second line contains $n$ integers $a_1, a_2, \dots, a_n$ ($1 \le a_i \le 5000$) — the number of balls of the $i$-th color.
Additional constraint on input: the total number of balls doesn't exceed $5000$.
Output
Print a single integer — the sum of values of all $2^n$ sets of colors, taken modulo $998\,244\,353$.
3
1 1 2
1
5
4
1 3 3 7
11
5
76
Note
Consider the first example. There are $8$ sets of colors:
- for the empty set, its value is $0$;
- for the set $\{1\}$, its value is $1$;
- for the set $\{2\}$, its value is $1$;
- for the set $\{3\}$, its value is $2$;
- for the set $\{1,2\}$, its value is $1$;
- for the set $\{1,3\}$, its value is $2$;
- for the set $\{2,3\}$, its value is $2$;
- for the set $\{1,2,3\}$, its value is $2$.
So, the sum of values over all $2^n$ sets of colors is $11$.