Description (leetcode)

You are given an integer array banned and two integers n and maxSum. You are choosing some number of integers following the below rules:

  • The chosen integers have to be in the range [1, n].
  • Each integer can be chosen at most once.
  • The chosen integers should not be in the array banned.
  • The sum of the chosen integers should not exceed maxSum.

Return the maximum number of integers you can choose following the mentioned rules.

Example 1:

Input: banned = [1,6,5], n = 5, maxSum = 6

Output: 2

Explanation: You can choose the integers 2 and 4.

2 and 4 are from the range [1, 5], both did not appear in banned, and their sum is 6, which did not exceed maxSum.

Example 2:

Input: banned = [1,2,3,4,5,6,7], n = 8, maxSum = 1

Output: 0

Explanation: You cannot choose any integer while following the mentioned conditions.

Example 3:

Input: banned = [11], n = 7, maxSum = 50

Output: 7

Explanation: You can choose the integers 1, 2, 3, 4, 5, 6, and 7.

They are from the range [1, 7], all did not appear in banned, and their sum is 28, which did not exceed maxSum.

Constraints:

  • 1 <= banned.length <= 10^4
  • 1 <= banned[i], n <= 10^4
  • 1 <= maxSum <= 10^9

submission

impl Solution {
    pub fn max_count(banned: Vec<i32>, n: i32, max_sum: i32) -> i32 {
        let banned: std::collections::HashSet<i32> = banned.into_iter().collect();
        (1..=n).filter(|x| !banned.contains(x))
            .scan(0, |sum, x| {
                *sum += x;
                Some(*sum)
            })
            .take_while(|&x| x <= max_sum)
            .count() as i32
    }
}