Commit e09c985

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Add ReverseStringUsingStack (#6452)

* Refactored ReverseStringUsingStack * Add ReverseStringUsingStack * Refactored ReverseStringUsingStack * Closes #6451

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+42

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src
- main/java/com/thealgorithms/strings
  - ReverseString.java
- test/java/com/thealgorithms/strings
  - ReverseStringTest.java

+42

-0

lines changed

Lines changed: 29 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -1,5 +1,7 @@`
`1`	`1`	`package com.thealgorithms.strings;`
`2`	`2`
	`3`	`+import java.util.Stack;`
	`4`	`+`
`3`	`5`	`/**`
`4`	`6`	`* Reverse String using different version`
`5`	`7`	`*/`
`@@ -57,4 +59,31 @@ public static String reverse3(String string) {`
`57`	`59`	`}`
`58`	`60`	`return sb.toString();`
`59`	`61`	`}`
	`62`	`+ /**`
	`63`	`+ * Reverses the given string using a stack.`
	`64`	`+ * This method uses a stack to reverse the characters of the string.`
	`65`	`+ * * @param str The input string to be reversed.`
	`66`	`+ * @return The reversed string.`
	`67`	`+ */`
	`68`	`+ public static String reverseStringUsingStack(String str) {`
	`69`	`+ // Check if the input string is null`
	`70`	`+ if (str == null) {`
	`71`	`+ throw new IllegalArgumentException("Input string cannot be null");`
	`72`	`+ }`
	`73`	`+ Stack<Character> stack = new Stack<>();`
	`74`	`+ StringBuilder reversedString = new StringBuilder();`
	`75`	`+ // Check if the input string is empty`
	`76`	`+ if (str.isEmpty()) {`
	`77`	`+ return str;`
	`78`	`+ }`
	`79`	`+ // Push each character of the string onto the stack`
	`80`	`+ for (char ch : str.toCharArray()) {`
	`81`	`+ stack.push(ch);`
	`82`	`+ }`
	`83`	`+ // Pop each character from the stack and append to the StringBuilder`
	`84`	`+ while (!stack.isEmpty()) {`
	`85`	`+ reversedString.append(stack.pop());`
	`86`	`+ }`
	`87`	`+ return reversedString.toString();`
	`88`	`+ }`
`60`	`89`	`}`

Lines changed: 13 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -1,8 +1,10 @@`
`1`	`1`	`package com.thealgorithms.strings;`
`2`	`2`
`3`	`3`	`import static org.junit.jupiter.api.Assertions.assertEquals;`
	`4`	`+import static org.junit.jupiter.api.Assertions.assertThrows;`
`4`	`5`
`5`	`6`	`import java.util.stream.Stream;`
	`7`	`+import org.junit.jupiter.api.Test;`
`6`	`8`	`import org.junit.jupiter.params.ParameterizedTest;`
`7`	`9`	`import org.junit.jupiter.params.provider.Arguments;`
`8`	`10`	`import org.junit.jupiter.params.provider.MethodSource;`
`@@ -31,4 +33,15 @@ public void testReverseString2(String input, String expectedOutput) {`
`31`	`33`	`public void testReverseString3(String input, String expectedOutput) {`
`32`	`34`	`assertEquals(expectedOutput, ReverseString.reverse3(input));`
`33`	`35`	`}`
	`36`	`+`
	`37`	`+ @ParameterizedTest`
	`38`	`+ @MethodSource("testCases")`
	`39`	`+ public void testReverseStringUsingStack(String input, String expectedOutput) {`
	`40`	`+ assertEquals(expectedOutput, ReverseString.reverseStringUsingStack(input));`
	`41`	`+ }`
	`42`	`+`
	`43`	`+ @Test`
	`44`	`+ public void testReverseStringUsingStackWithNullInput() {`
	`45`	`+ assertThrows(IllegalArgumentException.class, () -> ReverseString.reverseStringUsingStack(null));`
	`46`	`+ }`
`34`	`47`	`}`

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