From 1a391c2fe9b77904cde13d8aecb44cf3833673ba Mon Sep 17 00:00:00 2001
From: Aidar Djamalbek <70245901+adjamalbek@users.noreply.github.com>
Date: Tue, 1 Nov 2022 23:26:13 +0600
Subject: [PATCH] Add ValidParentheses (#3689)

---
 DIRECTORY.md                                  |  2 ++
 .../strings/ValidParentheses.java             | 33 +++++++++++++++++++
 .../strings/ValidParenthesesTest.java         | 24 ++++++++++++++
 3 files changed, 59 insertions(+)
 create mode 100644 src/main/java/com/thealgorithms/strings/ValidParentheses.java
 create mode 100644 src/test/java/com/thealgorithms/strings/ValidParenthesesTest.java

diff --git a/DIRECTORY.md b/DIRECTORY.md
index 38a38cf02..0345ff4e3 100644
--- a/DIRECTORY.md
+++ b/DIRECTORY.md
@@ -477,6 +477,7 @@
             * [ReverseStringRecursive](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/ReverseStringRecursive.java)
             * [Rotation](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/Rotation.java)
             * [Upper](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/Upper.java)
+            * [ValidParentheses](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/ValidParentheses.java)
             * [WordLadder](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/WordLadder.java)
             * zigZagPattern
               * [zigZagPattern](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/zigZagPattern/zigZagPattern.java)
@@ -648,6 +649,7 @@
             * [ReverseStringTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/ReverseStringTest.java)
             * [RotationTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/RotationTest.java)
             * [UpperTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/UpperTest.java)
+            * [ValidParenthesesTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/ValidParenthesesTest.java)
             * [WordLadderTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/WordLadderTest.java)
             * zigZagPattern
               * [zigZagPatternTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/zigZagPattern/zigZagPatternTest.java)
diff --git a/src/main/java/com/thealgorithms/strings/ValidParentheses.java b/src/main/java/com/thealgorithms/strings/ValidParentheses.java
new file mode 100644
index 000000000..e2b0f8e9b
--- /dev/null
+++ b/src/main/java/com/thealgorithms/strings/ValidParentheses.java
@@ -0,0 +1,33 @@
+package com.thealgorithms.strings;
+//        Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.
+//        An input string is valid if:
+//        Open brackets must be closed by the same type of brackets.
+//        Open brackets must be closed in the correct order.
+//        Every close bracket has a corresponding open bracket of the same type.
+
+
+public class ValidParentheses {
+	public static boolean isValid(String s) {
+		char[] stack = new char[s.length()];
+		int head = 0;
+		for(char c : s.toCharArray()) {
+			switch(c) {
+				case '{':
+				case '[':
+				case '(':
+					stack[head++] = c;
+					break;
+				case '}':
+					if(head == 0 || stack[--head] != '{') return false;
+					break;
+				case ')':
+					if(head == 0 || stack[--head] != '(') return false;
+					break;
+				case ']':
+					if(head == 0 || stack[--head] != '[') return false;
+					break;
+			}
+		}
+		return head == 0;
+	}
+}
diff --git a/src/test/java/com/thealgorithms/strings/ValidParenthesesTest.java b/src/test/java/com/thealgorithms/strings/ValidParenthesesTest.java
new file mode 100644
index 000000000..ab215f22e
--- /dev/null
+++ b/src/test/java/com/thealgorithms/strings/ValidParenthesesTest.java
@@ -0,0 +1,24 @@
+package com.thealgorithms.strings;
+
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.*;
+
+public class ValidParenthesesTest {
+	
+    @Test
+    void testOne() {
+        assertEquals(true, ValidParentheses.isValid("()"));
+    }
+  
+    @Test
+    void testTwo() {
+        assertEquals(true, ValidParentheses.isValid("()[]{}"));
+    }
+  
+  
+    @Test
+    void testThree() {
+        assertEquals(false, ValidParentheses.isValid("(]"));
+    }
+	
+}