---
tags: LeetCode
---

# 443. String Compression
Given an array of characters, compress it in-place.

The length after compression must always be smaller than or equal to the original array.

Every element of the array should be a character (not int) of length 1.

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

Follow up:
Could you solve it using only O(1) extra space?

Example 1:
Input:
["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:
"aa" is replaced by "a2". "bb" is replaced by "b2". "ccc" is replaced by "c3".

Example 2:
Input:
["a"]

Output:
Return 1, and the first 1 characters of the input array should be: ["a"]

Explanation:
Nothing is replaced.

Example 3:
Input:
["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:
Since the character "a" does not repeat, it is not compressed. "bbbbbbbbbbbb" is replaced by "b12".

Notice each digit has it's own entry in the array.

Note:
All characters have an ASCII value in [35, 126].
1 <= len(chars) <= 1000.

輸入範本如下

public class Solution {
    public int Compress(char[] chars) {
    }
}

### 直覺想法

252 ms	33.3 MB
You are here!
Your runtime beats 99.08 % of csharp submissions.
public int Compress(char[] chars)
{
    int pos = 0;
    for (int index = 1; index <= chars.Length; index++)
    {
        int count = 1;
        while (index < chars.Length && chars[index] == chars[index - 1])
        {
            count++;
            index++;
        }
        chars[pos++] = chars[index - 1]; // 移動 pos & 將正確的字元捕到正確的位置
        if (count > 1) // 數量一個時 , 不用特別標數量
        {
            foreach (var c in count.ToString().ToCharArray())
            {
                chars[pos++] = c;
            }
        }
    }
    return pos;
}

### Thank you!

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