class Solution {
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;
}
}