String Compression LeetCode Solution

Here, We see String Compression LeetCode Solution. This Leetcode problem is done in many programming languages like C++, Java, JavaScript, Python, etc. with different approaches.

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String Compression LeetCode Solution

String Compression LeetCode Solution

Problem Statement

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”.

String Compression LeetCode Solution C++

class Solution {
public:
    int compress(vector<char>& chars) {
        int ans = 0;
        for (int i = 0; i < chars.size();) {
            const char letter = chars[i];
            int count = 0;
            while (i < chars.size() && chars[i] == letter) {
                ++count;
                ++i;
            }
            chars[ans++] = letter;
            if (count > 1) {
                for (const char c : to_string(count)) {
                    chars[ans++] = c;
                }
            }
        }
        return ans;
    }
};Code language: PHP (php)

String Compression LeetCode Solution Java

class Solution {
  public int compress(char[] chars) {
    int ans = 0;
    for (int i = 0; i < chars.length;) {
      final char letter = chars[i];
      int count = 0;
      while (i < chars.length && chars[i] == letter) {
        ++count;
        ++i;
      }
      chars[ans++] = letter;
      if (count > 1) {
        for (final char c : String.valueOf(count).toCharArray()) {
          chars[ans++] = c;
        }
      }
    }
    return ans;
  }
}Code language: PHP (php)

String Compression Solution JavaScript

var compress = function(chars) {
    let i = 0;
    let j = 0;
    while (j < chars.length) {
        let count = 0;
        let curr = chars[j];
        while (j < chars.length && chars[j] === curr) {
            j++;
            count++;
        }
        chars[i++] = curr;
        if (count > 1) {
            for (let digit of count.toString()) {
                chars[i++] = digit;
            }
        }
    }
    return i;
};Code language: JavaScript (javascript)

String Compression Solution Python

class Solution(object):
    def compress(self, chars):
        ans = 0
        i = 0
        while i < len(chars):
            letter = chars[i]
            count = 0
            while i < len(chars) and chars[i] == letter:
                count += 1
                i += 1
            chars[ans] = letter
            ans += 1
            if count > 1:
                for c in str(count):
                    chars[ans] = c
                    ans += 1
        return ans
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