measifalam 🍉

src/javascript/dsa-functional Approach/linkedList.js

@@ -0,0 +1,145 @@
+function createNode(value) {
+  return {
+    value,
+    next: null
+  }
+}
+
+function createLinkedList() {
+  return {
+    head: null,
+    tail: null,
+    length: 0,
+
+    push(value) {
+      const node = createNode(value)
+
+      if (this.head === null) {
+        this.head = node
+        this.tail = node
+        this.length++
+        return node
+      }
+
+      this.tail.next = node
+      this.tail = node
+      this.length++
+
+      return node
+    },
+
+    pop() {
+      if (this.isEmpty()) {
+        return null
+      }
+
+      const node = this.tail
+
+      if (this.head === this.tail) {
+        this.head = null
+        this.tail = null
+        this.length--
+        return node
+      }
+
+      let current = this.head
+      let penultimate
+      while (current) {
+        if (current.next === this.tail) {
+          penultimate = current
+          break
+        }
+
+        current = current.next
+      }
+
+      penultimate.next = null
+      this.tail = penultimate
+      this.length--
+
+      return node
+    },
+
+    get(index) {
+      if (index < 0 || index > this.length - 1) {
+        return null
+      }
+
+      if (index === 0) {
+        return this.head
+      }
+
+      let current = this.head
+      let i = 0
+      while (i < index) {
+        i++
+        current = current.next
+      }
+
+      return current
+    },
+
+    delete(index) {
+      if (index < 0 || index > this.length - 1) {
+        return null
+      }
+
+      if (index === 0) {
+        const deleted = this.head
+
+        this.head = this.head.next
+        this.length--
+
+        return deleted
+      }
+
+      let current = this.head
+      let previous
+      let i = 0
+
+      while (i < index) {
+        i++
+        previous = current
+        current = current.next
+      }
+
+      const deleted = current
+      previous.next = current.next
+
+      if (previous.next === null) {
+        this.tail = previous
+      }
+
+      this.length--
+
+      return deleted
+    },
+
+    isEmpty() {
+      return this.length === 0
+    },
+
+    print() {
+      const values = []
+      let current = this.head
+
+      while (current) {
+        values.push(current.value)
+        current = current.next
+      }
+
+      return values.join(' => ')
+    }
+  }
+}
+
+const list = createLinkedList()
+const values = ['a', 'b', 'c', 'd', 'e']
+const nodes = values.map(val => list.push(val))
+
+list.pop()
+console.log(list.delete(1))
+console.log(list.print())
+
+exports.createNode = createNode
+exports.createLinkedList = createLinkedList