Home Computer Science Java Algorithm

213 · String Compression - LintCode

# Description

Implement a method to perform basic string compression using the counts of repeated characters. For example, the string aabcccccaaa would become a2b1c5a3 .

If the "compressed" string would not become smaller than the original string, your method should return the original string.

You can assume the string has only upper and lower case letters (a-z).

# Example

Example 1:

Input: str = "aabcccccaaa"
Output: "a2b1c5a3"

Example 2:

Input: str = "aabbcc"
Output: "aabbcc"

# Solution

public class Solution {
    /**
     * @param originalString: a string
     * @return: a compressed string
     */
    public String compress(String originalString) {
        String s = originalString;
        if (s == null || s.length() == 0) return s;
        int count = 1;
        char cur = s.charAt(0);
        String res = "";
        for (int i = 1; i < s.length(); i++) {
            if (cur == s.charAt(i)) {
                count++;
            } else {
                res = res + cur + count;
                count = 1;
                cur = s.charAt(i);
            }
        }
        //last one
        res = res + cur + count;
        if (res.length() >= s.length()) return s;
        return res;
    }
}