Medium

Quiz

#402 Remove K Digits

APPROACH

Given a string num representing a non-negative integer and an integer k, remove exactly k digits from num so that the remaining digits form the numerically smallest possible integer. Return the result as a string without leading zeros (returning "0" when the result is 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.

Example 3:

Input: num = "10", k = 2

Output: "0"

Explanation: Remove all the digits from the number and it is left with nothing which is 0.

1 of 4

1:00

What is the optimal approach for this problem?