-
Notifications
You must be signed in to change notification settings - Fork 2
/
StringCompression.java
85 lines (77 loc) · 2.77 KB
/
StringCompression.java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
package Leetcode;
/**
* @author kalpak
*
* 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.
*
*
* Follow up:
* Could you solve it using only O(1) 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 lower-case English letter, upper-case English letter, digit, or symbol.
*
*/
public class StringCompression {
public static int compress(char[] chars) {
int runningLength = 0;
for(int i = 0; i < chars.length;) {
chars[runningLength] = chars[i];
int j = i + 1;
// move j until the characters are same
while(j < chars.length && chars[j] == chars[i])
j++;
if(j - i > 1) {
String val = j - i + "";
for(char c : val.toCharArray()) {
runningLength++;
chars[runningLength] = c;
}
}
runningLength++;
i = j;
}
return runningLength;
}
public static void main(String[] args) {
char[] characters = new char[]{'a','a','a','b','b','a','a'};
System.out.println(compress(characters));
}
}