diff --git a/.gitignore b/.gitignore
index cbf6334..1f3eb30 100644
--- a/.gitignore
+++ b/.gitignore
@@ -28,3 +28,8 @@ Cargo.lock
 # Built Visual Studio Code Extensions
 *.vsix
 
+
+
+# Added by cargo
+
+/target
diff --git a/src/input/20_test1 b/src/input/20_test1
new file mode 100644
index 0000000..dd626a0
--- /dev/null
+++ b/src/input/20_test1
@@ -0,0 +1 @@
+()
\ No newline at end of file
diff --git a/src/input/20_test2 b/src/input/20_test2
new file mode 100644
index 0000000..e11a44a
--- /dev/null
+++ b/src/input/20_test2
@@ -0,0 +1 @@
+()[]{}
\ No newline at end of file
diff --git a/src/input/20_test3 b/src/input/20_test3
new file mode 100644
index 0000000..fd8a840
--- /dev/null
+++ b/src/input/20_test3
@@ -0,0 +1 @@
+(]
\ No newline at end of file
diff --git a/src/main.rs b/src/main.rs
index 4752654..99d5b1c 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -7,7 +7,10 @@ use solutions::*;
 
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn Error>> {
-    let problems: Vec<Box<dyn Solution + Sync>> = vec![Box::new(xx::XX {})];
+    let problems: Vec<Box<dyn Solution + Sync>> = vec![
+        Box::new(xx::XX {}),
+        Box::new(valid_parentheses::ValidParentheses {})
+    ];
 
     let mut t = vec![];
 
diff --git a/src/solutions/mod.rs b/src/solutions/mod.rs
index 5cec3eb..5aa562e 100644
--- a/src/solutions/mod.rs
+++ b/src/solutions/mod.rs
@@ -1,6 +1,7 @@
 use crate::utils::{self, get_input};
 use std::{error::Error, fmt::Display, time::SystemTime};
 
+pub mod valid_parentheses;
 pub mod xx;
 
 pub trait Solution {
diff --git a/src/solutions/valid_parentheses.rs b/src/solutions/valid_parentheses.rs
new file mode 100644
index 0000000..d0c5ca1
--- /dev/null
+++ b/src/solutions/valid_parentheses.rs
@@ -0,0 +1,98 @@
+use super::Solution;
+use std::{collections::HashMap, vec};
+
+pub struct ValidParentheses {}
+
+impl Solution for ValidParentheses {
+    fn solution(
+        &self,
+        input: &mut Vec<String>,
+    ) -> Result<Box<dyn std::fmt::Display + Sync>, Box<dyn std::error::Error>> {
+        // Pairs of parentheses to match
+        let pairs = HashMap::from([(')', '('), (']', '['), ('}', '{')]);
+
+        let mut stack: Vec<char> = vec![];
+
+        let line = input.get(0).unwrap();
+
+        for char in line.chars() {
+            // Check if the new character is a closing parentheses
+            if pairs.contains_key(&char) {
+                // If it is, is the last character in the stack the correct opening one
+                // If not, false, otherwise continue
+                if stack.last() == None || stack.pop().unwrap() != *pairs.get(&char).unwrap() {
+                    return Ok(Box::new(false));
+                }
+            } else {
+                stack.push(char)
+            }
+        }
+
+        // End stack will be empty if all parentheses are matched correctly
+        Ok(Box::new(stack.len() == 0))
+    }
+
+    fn get_id(&self) -> u8 {
+        20
+    }
+}
+
+impl ValidParentheses {}
+
+/// Test from puzzle input
+#[cfg(test)]
+mod test {
+    use super::*;
+    use crate::*;
+
+    #[test]
+    fn test1() {
+        let solution = valid_parentheses::ValidParentheses {};
+
+        //Complete the Challenge
+        let answer = solution
+            .solution(
+                utils::get_input(solution.get_id(), utils::InputType::Test1)
+                    .unwrap()
+                    .as_mut(),
+            )
+            .unwrap()
+            .to_string();
+
+        assert_eq!(answer, "true");
+    }
+
+    #[test]
+    fn test2() {
+        let solution = valid_parentheses::ValidParentheses {};
+
+        //Complete the Challenge
+        let answer = solution
+            .solution(
+                utils::get_input(solution.get_id(), utils::InputType::Test2)
+                    .unwrap()
+                    .as_mut(),
+            )
+            .unwrap()
+            .to_string();
+
+        assert_eq!(answer, "true");
+    }
+
+    #[test]
+    fn test3() {
+        let solution = valid_parentheses::ValidParentheses {};
+
+        //Complete the Challenge
+        let answer = solution
+            .solution(
+                utils::get_input(solution.get_id(), utils::InputType::Test3)
+                    .unwrap()
+                    .as_mut(),
+            )
+            .unwrap()
+            .to_string();
+
+        assert_eq!(answer, "false");
+    }
+}