443. String Compression

Problem No.443 String Compression
Question Link- https://leetcode.com/problems/string-compression/description/?envType=study-plan-v2&envId=leetcode-75

Solution in Java:
class Solution {
    public int compress(char[] chars) {
        StringBuilder sb = new StringBuilder();
        int i = 1;
        int count = 1;
        sb.append(chars[0]);

        while(i< chars.length){
            if( chars[i] == chars[i-1]){
                count++;
            }
            else{
                if (count > 1){
                    sb.append(count);
                }
                sb.append(chars[i]);
                count = 1;
            }
            i++;
        }
        if (count >1){
            sb.append(count);
        }
        for( int j=0; j<sb.length(); j++){
            chars[j] = sb.charAt(j);
        }
        return sb.length();
    }
}

Time Complexity: O(n)
Space Complexity: O(1)