Given string num representing a non-negative integer num, and an integer k, return the smallest possible integer after removing k digits from num.
Examples
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.
Constraints
1 <= k <= num.length <= 105
num consists of only digits.
num does not have any leading zeros except for the zero itself.
402. Remove K Digits
Medium
30 Points
String
Stack
Greedy
Monotonic Stack
Given string num representing a non-negative integer num, and an integer k, return the smallest possible integer after removing k digits from num.
Examples
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.
Constraints
1 <= k <= num.length <= 105
num consists of only digits.
num does not have any leading zeros except for the zero itself.