From a31b0d7cdf7e0286816b9a46adfe65bad0341c6a Mon Sep 17 00:00:00 2001
From: Matej Focko <me@mfocko.xyz>
Date: Fri, 23 Aug 2024 22:56:22 +0200
Subject: [PATCH] =?UTF-8?q?java:=20add=20=C2=AB394.=20Decode=20String?=
 =?UTF-8?q?=C2=BB?=
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Signed-off-by: Matej Focko <me@mfocko.xyz>
---
 java/decode-string.java | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)
 create mode 100644 java/decode-string.java

diff --git a/java/decode-string.java b/java/decode-string.java
new file mode 100644
index 0000000..367d857
--- /dev/null
+++ b/java/decode-string.java
@@ -0,0 +1,35 @@
+import java.util.Stack;
+
+class Solution {
+  private record StackEntry(int count, StringBuilder str) {
+    @Override
+    public String toString() {
+      return new StringBuilder().repeat(str(), count()).toString();
+    }
+  }
+
+  public String decodeString(String s) {
+    var stack = new Stack<StackEntry>();
+    stack.push(new StackEntry(1, new StringBuilder()));
+
+    int count = 0;
+    for (int i = 0; i < s.length(); ++i) {
+      var c = s.charAt(i);
+
+      if (c == '[') {
+        stack.push(new StackEntry(count, new StringBuilder()));
+        count = 0;
+      } else if (c == ']') {
+        var last = stack.pop();
+        stack.peek().str().append(last);
+      } else if (Character.isDigit(c)) {
+        count *= 10;
+        count += c - '0';
+      } else {
+        stack.peek().str().append(c);
+      }
+    }
+
+    return stack.pop().toString();
+  }
+}