Leetcode - Remove K Digits

https://leetcode.com/problems/remove-k-digits/

Given a non-negative integer num represented as a string, remove k digits from the number so that the new number is the smallest possible.

Note:

• The length of num is less than 10002 and will be ≥ k.
• The given num does not contain any leading zero.

Example 1:

Input: num = "1432219", k = 3
Output: "1219"
Explanation: Remove the three digits 4, 3, and 2 to form the new number 1219 which is the smallest.

Example 2:

Input: num = "10200", k = 1
Output: "200"
Explanation: Remove the leading 1 and the number is 200. Note that the output must not contain leading zeroes.

func removeKdigits(num string, k int) string {
    if k == len(num) {
        return "0"
    }
    stack := []byte{}
    i := 0
    for i < len(num) {
        for k > 0 && len(stack) != 0 && stack[len(stack)-1] > num[i] {
            stack = stack[:len(stack)-1]
            k--
        }
        stack = append(stack, num[i])
        i++
    }
    for k > 0 {
        stack = stack[:len(stack)-1]
        k--
    }
    i = 0
    for i < len(stack) && stack[i] == '0' {
        i++
    }
        
    stack = stack[i:]
    if len(stack) == 0 {
        return "0"
    }
    return string(stack)
}

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