stacks

Author: Carlos Green

Chapter4Stacks/fact.js

@@ -0,0 +1,16 @@
+const Stack = require("./stack.js")
+
+function fact(n) {
+  var s = new Stack()
+  while(n > 1) {
+    s.push(n--)
+  }
+  var product = 1
+  while(s.length() > 0) {
+    product *= s.pop()
+  }
+  return product
+}
+
+console.log(fact(5), 5)
+console.log(fact(20), 20)

Chapter4Stacks/factorial.js

@@ -0,0 +1,11 @@
+function factorial(n) {
+  if (n === 0) {
+    return 1
+  } else {
+    return n * factorial(n - 1)
+  }
+}
+
+// 5! = 5 * 4 * 3 * 2 * 1 = 120
+console.log(factorial(5), 5)
+console.log(factorial(20), 20)

Chapter4Stacks/isPalindrome.js

@@ -0,0 +1,33 @@
+const Stack = require('./stack.js')
+
+function isPalindrome(word) {
+  var s = new Stack()
+  for (var i = 0; i < word.length; ++i) {
+    s.push(word[i])
+  }
+  var rword = "";
+  while(s.length() > 0) {
+    rword += s.pop()
+  }
+  if (word == rword) {
+    return true
+  } else {
+    return false
+  }
+}
+
+var word = "hello"
+
+if (isPalindrome(word)) {
+  console.log(word + " is a palindrome.")
+} else {
+  console.log(word + " is not a palindrome.")
+}
+
+var word = "racecar"
+
+if (isPalindrome(word)) {
+  console.log(word + " is a palindrome.")
+} else {
+  console.log(word + " is not a palindrome.")
+}

Chapter4Stacks/multiBase.js

@@ -0,0 +1,27 @@
+const Stack = require('./stack.js');
+
+function multiBase(num, base) {
+  var s = new Stack();
+  do {
+    s.push(num % base);
+    num = Math.floor((num /= base));
+  } while (num > 0);
+
+  var converted = '';
+  while (s.length() > 0) {
+    converted += s.pop();
+  }
+  return converted;
+}
+
+var num = 32
+var base = 2
+var newNum = multiBase(num, base)
+
+console.log(num + " converted to base " + base + " is " + newNum)
+
+num = 125
+base = 8
+
+var newNum = multiBase(num, base)
+console.log(num + " converted to base " + base + " is " + newNum)

Chapter4Stacks/stack.js

@@ -18,19 +18,7 @@ function Stack() {
       this.dataStore.pop()
     }
     this.top = 0
-    console.log(this.dataStore, 'data')
   }
 }
 
-let st1 = new Stack()
-
-st1.push('nice')
-st1.push('cool')
-st1.push('sweet')
-st1.push('nice')
-
-console.log(st1.dataStore, 'store')
-st1.clear()
-console.log(st1.dataStore, 'store')
-st1.push('nice')
-console.log(st1.dataStore, 'store')
+module.exports = Stack