#196 · #443 · String Compression(压缩字符串)

Given an array of characters chars, compress it in place using run-length encoding: for each group of consecutive identical characters, write the character followed by the group length (omitted when the length is 1). Return the new length. Constraints: 1 <= chars.length <= 2000; chars[i] is a lowercase letter, uppercase letter, digit or symbol.