lec4_sortVowels.cpp

https://leetcode.com/problems/sort-vowels-in-a-string/submissions/1297978511/
class Solution {
public:
    string sortVowels(string s) {

        vector<int>lower( 26 , 0); 
        vector<int>upper( 26  , 0);

        for(int i = 0 ; i<s.size(); i++)
        {
            if(s[i] == 'a' || s[i] == 'e'|| s[i] == 'i'|| s[i] == 'o' || s[i] == 'u' )
            {
                lower[s[i] - 'a']++;
                s[i]= '#';
            }
            else if(s[i] == 'A' || s[i] == 'E'|| s[i] == 'I'|| s[i] == 'O' || s[i] == 'U' )
            {
                upper[s[i] - 'A']++;
                s[i]= '#';
            }
        }

        string ans;
        for(int i = 0 ; i<26; i++)
        {
            char c = 'A' + i ;
            while(upper[i])
            {
                ans+=c ;
                upper[i]--;
            }
        }
        for(int i = 0 ; i<26; i++)
        {
            char c = 'a' + i ;
            while(lower[i])
            {
                ans+=c ;
                lower[i]--;
            }
        }
        int first = 0 , second = 0 ;
        while(second<ans.size())
        {
            if(s[first] == '#')
            {
                s[first] = ans[second];
                second++;
            }
            first++;
        }

        return s;
    }
};