g0401_0500.s0443_string_compression

Class Solution

java.lang.Object

g0401_0500.s0443_string_compression.Solution

public class Solution
extends Object

443 - String Compression.

Medium

Given an array of characters chars, compress it using the following algorithm:

Begin with an empty string s. For each group of consecutive repeating characters in chars:

• If the group’s length is 1, append the character to s.
• Otherwise, append the character followed by the group’s length.

The compressed string s should not be returned separately , but instead, be stored **in the input character array chars **. Note that group lengths that are 10 or longer will be split into multiple characters in chars.

After you are done modifying the input array , return the new length of the array.

You must write an algorithm that uses only constant extra space.

Example 1:

Input: chars = [“a”,“a”,“b”,“b”,“c”,“c”,“c”]

Output: Return 6, and the first 6 characters of the input array should be: [“a”,“2”,“b”,“2”,“c”,“3”]

Explanation: The groups are “aa”, “bb”, and “ccc”. This compresses to “a2b2c3”.

Example 2:

Input: chars = [“a”]

Output: Return 1, and the first character of the input array should be: [“a”]

Explanation: The only group is “a”, which remains uncompressed since it’s a single character.

Example 3:

Input: chars = [“a”,“b”,“b”,“b”,“b”,“b”,“b”,“b”,“b”,“b”,“b”,“b”,“b”]

Output: Return 4, and the first 4 characters of the input array should be: [“a”,“b”,“1”,“2”].

Explanation: The groups are “a” and “bbbbbbbbbbbb”. This compresses to “ab12”.

Example 4:

Input: chars = [“a”,“a”,“a”,“b”,“b”,“a”,“a”]

Output: Return 6, and the first 6 characters of the input array should be: [“a”,“3”,“b”,“2”,“a”,“2”].

Explanation: The groups are “aaa”, “bb”, and “aa”. This compresses to “a3b2a2”. Note that each group is independent even if two groups have the same character.

Constraints:

• 1 <= chars.length <= 2000
• chars[i] is a lowercase English letter, uppercase English letter, digit, or symbol.

Constructor Summary

Constructors

Constructor and Description
Solution()

Method Summary

Modifier and Type	Method and Description
int	compress(char[] chars)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Solution

public Solution()

Method Detail

compress

public int compress(char[] chars)