diff --git a/chapter01/1.1 - Is Unique/isUnique-2.js b/chapter01/1.1 - Is Unique/isUnique-2.js
new file mode 100644
index 0000000..76313a1
--- /dev/null
+++ b/chapter01/1.1 - Is Unique/isUnique-2.js	
@@ -0,0 +1,28 @@
+const isUniqueCharacters = (input) => {
+  if (input.length === 0) {
+    return true;
+  }
+  // Based on ASCII string
+  if (input.length > 128) {
+    return false;
+  }
+
+  const uniqueCharacters = {};
+
+  for (i = 0; i < input.length; i++) {
+    const character = input[i];
+    if (uniqueCharacters[character]) {
+      return false;
+    }
+
+    if (!uniqueCharacters[character]) {
+      uniqueCharacters[character] = 1;
+    }
+  }
+
+  return true;
+};
+
+console.log(isUniqueCharacters("abcde"));
+console.log(isUniqueCharacters("abcdefghh"));
+console.log(isUniqueCharacters(""));
diff --git a/chapter01/1.2 - Check Perm/checkPermute-2.js b/chapter01/1.2 - Check Perm/checkPermute-2.js
new file mode 100644
index 0000000..f110fac
--- /dev/null
+++ b/chapter01/1.2 - Check Perm/checkPermute-2.js	
@@ -0,0 +1,33 @@
+const checkPermute = (stringA, stringB) => {
+  if (stringA.length !== stringB.length) {
+    return false;
+  }
+  const letters = {};
+  for (i = 0; i < stringA.length; i++) {
+    const letter = stringA[i];
+    if (!letters[letter]) {
+      letters[letter] = 1;
+    } else {
+      letters[letter] += 1;
+    }
+  }
+
+  for (i = 0; i < stringB.length; i++) {
+    const letter = stringB[i];
+    if (!letters[letter]) {
+      return false;
+    }
+    letters[letter] -= 1;
+
+    if (letters[letter] < 0) {
+      return false;
+    }
+  }
+
+  return true;
+};
+
+console.log(checkPermute("a", "bbbb"));
+console.log(checkPermute("aba", "baa"));
+console.log(checkPermute("aaaa", "bbbb"));
+console.log(checkPermute("  a", "a  "));
diff --git a/chapter01/1.3 - URLify/urlify-4.js b/chapter01/1.3 - URLify/urlify-4.js
new file mode 100644
index 0000000..752620a
--- /dev/null
+++ b/chapter01/1.3 - URLify/urlify-4.js	
@@ -0,0 +1,10 @@
+const urlify = (input) => {
+  return [...input].reduce((previousValue, character) => {
+    if (character === " ") {
+      return (previousValue += "%20");
+    }
+    return (previousValue += character);
+  }, "");
+};
+
+console.log(urlify("Mr John Smith"), "Mr%20John%20Smith");