-
Notifications
You must be signed in to change notification settings - Fork 43
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
- Loading branch information
Showing
7 changed files
with
350 additions
and
16 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
157 changes: 157 additions & 0 deletions
157
leetcode_java/src/main/java/LeetCodeJava/Stack/DecodeString.java
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,157 @@ | ||
| package LeetCodeJava.Stack; | ||
|
|
||
| // https://leetcode.com/problems/decode-string/description/ | ||
| // https://leetcode.ca/all/394.html | ||
|
|
||
| import java.util.ArrayDeque; | ||
| import java.util.Deque; | ||
| import java.util.Stack; | ||
|
|
||
| /** | ||
| * 394. Decode String | ||
| * Given an encoded string, return its decoded string. | ||
| * <p> | ||
| * The encoding rule is: k[encoded_string], where the encoded_string inside the square brackets is being repeated exactly k times. Note that k is guaranteed to be a positive integer. | ||
| * <p> | ||
| * You may assume that the input string is always valid; No extra white spaces, square brackets are well-formed, etc. | ||
| * <p> | ||
| * Furthermore, you may assume that the original data does not contain any digits and that digits are only for those repeat numbers, k. For example, there won't be input like 3a or 2[4]. | ||
| * <p> | ||
| * Examples: | ||
| * <p> | ||
| * s = "3[a]2[bc]", return "aaabcbc". | ||
| * s = "3[a2[c]]", return "accaccacc". | ||
| * s = "2[abc]3[cd]ef", return "abcabccdcdcdef". | ||
| * <p> | ||
| * <p> | ||
| * Difficulty: | ||
| * Medium | ||
| * Lock: | ||
| * Normal | ||
| * Company: | ||
| * Amazon AppDynamics Apple Atlassian Bloomberg Cisco Coupang Cruise Automation Facebook Google Huawei Microsoft Oracle Salesforce Snapchat Tencent VMware Yahoo Yelp | ||
| */ | ||
| public class DecodeString { | ||
|
|
||
| // V0 | ||
| // IDEA : STACK | ||
| // TODO : optimize code | ||
| public String decodeString(String s) { | ||
| if (s.isEmpty()) { | ||
| return null; | ||
| } | ||
| // init | ||
| Stack<String> stack = new Stack<>(); // ?? | ||
| StringBuilder sb = new StringBuilder(); | ||
| String A_TO_Z = "abcdefghijklmnopqrstuvwxyz"; | ||
| for (String x : s.split("")) { | ||
| //System.out.println(">>> x = " + x); | ||
| String tmp = ""; | ||
| StringBuilder tmpSb = new StringBuilder(); | ||
| if (!x.equals("]")) { | ||
| if (!x.equals("[")) { | ||
| stack.add(x); | ||
| } | ||
| } else { | ||
| // pop all elements from stack, multiply, and add to res | ||
| while (!stack.isEmpty()) { | ||
| String cur = stack.pop(); // ?? | ||
| if (A_TO_Z.contains(cur)) { | ||
| tmp = cur + tmp; | ||
| } else { | ||
| tmp = getMultiplyStr(tmp, Integer.parseInt(cur)); | ||
| } | ||
| } | ||
| } | ||
| sb.append(tmp); | ||
| } | ||
|
|
||
| StringBuilder tmpSb = new StringBuilder(); | ||
|
|
||
| // add remaining stack element to result | ||
| while (!stack.isEmpty()) { | ||
| tmpSb.append(stack.pop()); | ||
| } | ||
|
|
||
| sb.append(tmpSb.reverse()); | ||
| return sb.toString(); | ||
| } | ||
|
|
||
| private String getMultiplyStr(String cur, Integer multiply) { | ||
| StringBuilder sb = new StringBuilder(); | ||
| for (int x = 0; x < multiply; x++) { | ||
| sb.append(cur); | ||
| } | ||
| return sb.toString(); | ||
| } | ||
|
|
||
|
|
||
| // V1 | ||
| // https://leetcode.ca/2016-12-28-394-Decode-String/ | ||
| public String decodeString_1(String s) { | ||
| Deque<Integer> s1 = new ArrayDeque<>(); | ||
| Deque<String> s2 = new ArrayDeque<>(); | ||
| int num = 0; | ||
| String res = ""; | ||
| for (char c : s.toCharArray()) { | ||
| if ('0' <= c && c <= '9') { | ||
| num = num * 10 + c - '0'; | ||
| } else if (c == '[') { | ||
| s1.push(num); | ||
| s2.push(res); | ||
| num = 0; | ||
| res = ""; | ||
| } else if (c == ']') { | ||
| StringBuilder t = new StringBuilder(); | ||
| for (int i = 0, n = s1.pop(); i < n; ++i) { | ||
| t.append(res); | ||
| } | ||
| res = s2.pop() + t.toString(); | ||
| } else { | ||
| res += String.valueOf(c); | ||
| } | ||
| } | ||
| return res; | ||
| } | ||
|
|
||
| // V2 | ||
| // IDEA : STACK (gpt) | ||
| public static String decodeString_2(String s) { | ||
| if (s.isEmpty()) { | ||
| return ""; | ||
| } | ||
|
|
||
| // Stacks for numbers and strings | ||
| Stack<Integer> countStack = new Stack<>(); | ||
| Stack<StringBuilder> stringStack = new Stack<>(); | ||
| StringBuilder currentString = new StringBuilder(); | ||
| int k = 0; // Temporary variable for number parsing | ||
|
|
||
| for (char ch : s.toCharArray()) { | ||
| if (Character.isDigit(ch)) { | ||
| // Build the number (support for multi-digit numbers) | ||
| k = k * 10 + (ch - '0'); | ||
| } else if (ch == '[') { | ||
| // Push current number and string onto their respective stacks | ||
| countStack.push(k); | ||
| stringStack.push(currentString); | ||
| currentString = new StringBuilder(); // Start a new substring | ||
| k = 0; // Reset the number | ||
| } else if (ch == ']') { | ||
| // Decode substring | ||
| int count = countStack.pop(); | ||
| StringBuilder decodedString = stringStack.pop(); | ||
| for (int i = 0; i < count; i++) { | ||
| decodedString.append(currentString); | ||
| } | ||
| currentString = decodedString; // Update current string | ||
| } else { | ||
| // Append characters to current string | ||
| currentString.append(ch); | ||
| } | ||
| } | ||
|
|
||
| return currentString.toString(); | ||
| } | ||
|
|
||
| } |
Oops, something went wrong.