20.02.2024
268. Missing Number easy
blog post
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Problem TLDR
Missing in [0…n] number.
Intuition
There are several ways to find it:
subtracting sums
doing xor
computing sum with a math
n * (n + 1) / 2
Approach
Write what is easier for you, then learn the other solutions. Xor especially.
Complexity
Time complexity:
O(n)Space complexity:
O(1)
Code
fun missingNumber(nums: IntArray): Int =
(1..nums.size).sum() - nums.sum()
pub fn missing_number(nums: Vec<i32>) -> i32 {
nums.iter().enumerate().map(|(i, n)| i as i32 + 1 - n).sum()
}