Lexicographically Minimum String After Removing Stars | Leetcode 3170

class Solution {
public:
    string clearStars(string s) {
        vector<vector<int>> char_pos(26);
        for(int i=0;s[i];++i){
            if(s[i]=='*'){
                for(int j=0;j<26;++j){
                    if(char_pos[j].size()>0){
                        s[char_pos[j].back()]='*';
                        char_pos[j].pop_back();
                        break;
                    }
                }
            }else{
                char_pos[s[i]-'a'].push_back(i);
            }
        }
        string res;
        for(char c: s)
            if(c!='*')
                res.push_back(c);
        return res;
    }
};
/*
//JAVA
import java.util.*;

class Solution {
    public String clearStars(String s) {
        List<List<Integer>> charPos = new ArrayList<>();
        for (int i = 0; i < 26; i++) {
            charPos.add(new ArrayList<>());
        }
        
        char[] arr = s.toCharArray();
        
        for (int i = 0; i < arr.length; i++) {
            if (arr[i] == '*') {
                for (int j = 0; j < 26; j++) {
                    if (!charPos.get(j).isEmpty()) {
                        int pos = charPos.get(j).remove(charPos.get(j).size() - 1);
                        arr[pos] = '*';
                        break;
                    }
                }
            } else {
                charPos.get(arr[i] - 'a').add(i);
            }
        }
        
        StringBuilder res = new StringBuilder();
        for (char c : arr) {
            if (c != '*') {
                res.append(c);
            }
        }
        
        return res.toString();
    }
}

#Python
class Solution:
    def clearStars(self, s: str) -> str:
        char_pos = [[] for _ in range(26)]
        s_list = list(s)
        
        for i, c in enumerate(s_list):
            if c == '*':
                for j in range(26):
                    if char_pos[j]:
                        pos = char_pos[j].pop()
                        s_list[pos] = '*'
                        break
            else:
                char_pos[ord(c) - ord('a')].append(i)
        
        res = []
        for c in s_list:
            if c != '*':
                res.append(c)
        
        return ''.join(res)
*/

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