791. Custom Sort String

// 791. Custom Sort String
// Runtime: 0 ms, faster than 100.00% of Java online submissions for Custom Sort String.
// Memory Usage: 37.3 MB, less than 58.42% of Java online submissions for Custom Sort String.

class Solution {
    public String customSortString(String order, String str) {
        // String result="";
        StringBuilder sb=new StringBuilder();
        
         int [] c = new int[26];

        for(char ch:str.toCharArray())
        {
            c[ch-'a']++;
        }

		for(char ch:order.toCharArray())
        {
            int j = c[ch-'a'];
            while(j-->0)
            {
               sb.append(ch);
            }
            c[ch-'a']=0;
        }

        for(int i=0;i<26;i++){
            if(c[i]>0)
            {
                int x = c[i];
                while(x-->0)
                {
                    char ch = (char)(i+'a');
                    sb.append(ch);
                }
            }
        }

        return sb.toString();
    }
}