3174. Clear Digits

You are given a string s.

Your task is to remove all digits by doing this operation repeatedly:

• Delete the first digit and the closest non-digit character to its left.

Return the resulting string after removing all digits.

 Example 1:

Input: s = "abc"

Output: "abc"

Explanation:

There is no digit in the string.

Example 2:

Input: s = "cb34"

Output: ""

Explanation:

First, we apply the operation on s[2], and s becomes "c4".

Then we apply the operation on s[1], and s becomes "".

 Constraints:

• 1 <= s.length <= 100
• s consists only of lowercase English letters and digits.
• The input is generated such that it is possible to delete all digits.

Solution 1: Stack + Simulation

JAVA

• class Solution {
      public String clearDigits(String s) {
          StringBuilder stk = new StringBuilder();
          for (char c : s.toCharArray()) {
              if (Character.isDigit(c)) {
                  stk.deleteCharAt(stk.length() - 1);
              } else {
                  stk.append(c);
              }
          }
          return stk.toString();
      }
  }

C++

• class Solution {
  public:
      string clearDigits(string s) {
          string stk;
          for (char c : s) {
              if (isdigit(c)) {
                  stk.pop_back();
              } else {
                  stk.push_back(c);
              }
          }
          return stk;
      }
  };

PYTHON

• class Solution:
      def clearDigits(self, s: str) -> str:
          stk = []
          for c in s:
              if c.isdigit():
                  if stk:
                      stk.pop()
              else:
                  stk.append(c)
          return "".join(stk)