public int compress(char[] chars) {

// https://leetcode.com/problems/string-compression/solution/

int anchor = 0, write = 0;

for (int read = 0; read < chars.length; read++) {

if (read + 1 == chars.length || chars[read + 1] != chars[read]) {

chars[write++] = chars[anchor];

if (read > anchor) {

for (char c: ("" + (read - anchor + 1)).toCharArray()) {

chars[write++] = c;

}

}

anchor = read + 1;

}

}

return write;

}

}