diff --git a/.gitignore b/.gitignore
index 0794134..7d49510 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,3 +3,4 @@ build
 lib
 yarn-error.log
 .idea
+.nyc_output
diff --git a/.run/Template Mocha.run.xml b/.run/Template Mocha.run.xml
new file mode 100644
index 0000000..72dd382
--- /dev/null
+++ b/.run/Template Mocha.run.xml	
@@ -0,0 +1,14 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="true" type="mocha-javascript-test-runner">
+    <node-interpreter>project</node-interpreter>
+    <node-options />
+    <mocha-package>$PROJECT_DIR$/node_modules/ts-mocha</mocha-package>
+    <working-directory>$PROJECT_DIR$</working-directory>
+    <pass-parent-env>true</pass-parent-env>
+    <ui>bdd</ui>
+    <extra-mocha-options />
+    <test-kind>PATTERN</test-kind>
+    <test-pattern>$PROJECT_DIR$/test/*.spec.ts</test-pattern>
+    <method v="2" />
+  </configuration>
+</component>
diff --git a/src/fixedMerkleTree.ts b/src/fixedMerkleTree.ts
new file mode 100644
index 0000000..4c4c6f9
--- /dev/null
+++ b/src/fixedMerkleTree.ts
@@ -0,0 +1,238 @@
+import {
+  defaultHash,
+  Element,
+  HashFunction,
+  MerkleTreeOptions,
+  ProofPath,
+  SerializedTreeState,
+  TreeEdge,
+} from './'
+
+
+export default class MerkleTree {
+  get layers(): Array<Element[]> {
+    return this._layers.slice()
+  }
+
+  set layers(value: Array<Element[]>) {
+    this._layers = value
+  }
+
+  levels: number
+  capacity: number
+  private _hashFn: HashFunction<Element>
+  private zeroElement: Element
+  private _zeros: Element[]
+  private _layers: Array<Element[]>
+
+  constructor(levels: number, elements: Element[] = [], {
+    hashFunction = defaultHash,
+    zeroElement = 0,
+  }: MerkleTreeOptions = {}) {
+    this.levels = levels
+    this.capacity = 2 ** levels
+    if (elements.length > this.capacity) {
+      throw new Error('Tree is full')
+    }
+    this._hashFn = hashFunction
+    this.zeroElement = zeroElement
+
+    this._layers = []
+    this._layers[0] = elements.slice()
+    this._buildZeros()
+    this._rebuild()
+  }
+
+  private _buildZeros() {
+    this._zeros = [this.zeroElement]
+    for (let i = 1; i <= this.levels; i++) {
+      this._zeros[i] = this._hashFn(this._zeros[i - 1], this._zeros[i - 1])
+    }
+  }
+
+  _rebuild() {
+    for (let level = 1; level <= this.levels; level++) {
+      this._layers[level] = []
+      for (let i = 0; i < Math.ceil(this._layers[level - 1].length / 2); i++) {
+        this._layers[level][i] = this._hashFn(
+          this._layers[level - 1][i * 2],
+          i * 2 + 1 < this._layers[level - 1].length
+            ? this._layers[level - 1][i * 2 + 1]
+            : this._zeros[level - 1],
+        )
+      }
+    }
+  }
+
+  /**
+   * Get tree root
+   */
+  root(): Element {
+    return this._layers[this.levels][0] ?? this._zeros[this.levels]
+  }
+
+  /**
+   * Insert new element into the tree
+   * @param element Element to insert
+   */
+  insert(element: Element) {
+    if (this._layers[0].length >= this.capacity) {
+      throw new Error('Tree is full')
+    }
+    this.update(this._layers[0].length, element)
+  }
+
+  /**
+   * Insert multiple elements into the tree.
+   * @param {Array} elements Elements to insert
+   */
+  bulkInsert(elements: Element[]) {
+    if (!elements.length) {
+      return
+    }
+
+    if (this._layers[0].length + elements.length > this.capacity) {
+      throw new Error('Tree is full')
+    }
+    // First we insert all elements except the last one
+    // updating only full subtree hashes (all layers where inserted element has odd index)
+    // the last element will update the full path to the root making the tree consistent again
+    for (let i = 0; i < elements.length - 1; i++) {
+      this._layers[0].push(elements[i])
+      let level = 0
+      let index = this._layers[0].length - 1
+      while (index % 2 === 1) {
+        level++
+        index >>= 1
+        this._layers[level][index] = this._hashFn(
+          this._layers[level - 1][index * 2],
+          this._layers[level - 1][index * 2 + 1],
+        )
+      }
+    }
+    this.insert(elements[elements.length - 1])
+  }
+
+  /**
+   * Change an element in the tree
+   * @param {number} index Index of element to change
+   * @param element Updated element value
+   */
+  update(index: number, element: Element) {
+    if (isNaN(Number(index)) || index < 0 || index > this._layers[0].length || index >= this.capacity) {
+      throw new Error('Insert index out of bounds: ' + index)
+    }
+    this._layers[0][index] = element
+    for (let level = 1; level <= this.levels; level++) {
+      index >>= 1
+      this._layers[level][index] = this._hashFn(
+        this._layers[level - 1][index * 2],
+        index * 2 + 1 < this._layers[level - 1].length
+          ? this._layers[level - 1][index * 2 + 1]
+          : this._zeros[level - 1],
+      )
+    }
+  }
+
+  /**
+   * Get merkle path to a leaf
+   * @param {number} index Leaf index to generate path for
+   * @returns {{pathElements: Object[], pathIndex: number[]}} An object containing adjacent elements and left-right index
+   */
+  path(index: Element): ProofPath {
+    if (isNaN(Number(index)) || index < 0 || index >= this._layers[0].length) {
+      throw new Error('Index out of bounds: ' + index)
+    }
+    let elIndex = +index
+    const pathElements: Element[] = []
+    const pathIndices: number[] = []
+    const pathPositions: number [] = []
+    for (let level = 0; level < this.levels; level++) {
+      pathIndices[level] = elIndex % 2
+      const leafIndex = elIndex ^ 1
+      if (leafIndex < this._layers[level].length) {
+        pathElements[level] = this._layers[level][leafIndex]
+        pathPositions[level] = leafIndex
+      } else {
+        pathElements[level] = this._zeros[level]
+        pathPositions[level] = 0
+      }
+      elIndex >>= 1
+    }
+    return {
+      pathElements,
+      pathIndices,
+      pathPositions,
+    }
+  }
+
+  /**
+   * Find an element in the tree
+   * @param element An element to find
+   * @param comparator A function that checks leaf value equality
+   * @returns {number} Index if element is found, otherwise -1
+   */
+  indexOf(element: Element, comparator?: <T, R> (arg0: T, arg1: T) => R): number {
+    if (comparator) {
+      return this._layers[0].findIndex((el) => comparator<Element, number>(element, el))
+    } else {
+      return this._layers[0].indexOf(element)
+    }
+  }
+
+  getTreeEdge(edgeElement: Element, index?: number): TreeEdge {
+    if (edgeElement === 'undefined') {
+      throw new Error('element is required')
+    }
+    let edgeIndex: number
+    if (!Number.isInteger(index)) {
+      index = -1
+      const leaves = this._layers[0]
+      index = leaves.indexOf(edgeElement)
+      edgeIndex = index
+    }
+
+    if (index <= -1) {
+      return null
+    }
+    const edgePath = this.path(index)
+    return { edgePath, edgeElement, edgeIndex }
+  }
+
+  /**
+   * Returns a copy of non-zero tree elements.
+   */
+  get elements() {
+    return this._layers[0].slice()
+  }
+
+  /**
+   * Returns a copy of n-th zero elements array
+   */
+  get zeros() {
+    return this._zeros.slice()
+  }
+
+  /**
+   * Serialize entire tree state including intermediate layers into a plain object
+   * Deserializing it back will not require to recompute any hashes
+   * Elements are not converted to a plain type, this is responsibility of the caller
+   */
+  serialize(): SerializedTreeState {
+    return {
+      levels: this.levels,
+      _zeros: this._zeros,
+      _layers: this._layers,
+    }
+  }
+
+  /**
+   * Deserialize data into a MerkleTree instance
+   * Make sure to provide the same hashFunction as was used in the source tree,
+   * otherwise the tree state will be invalid
+   */
+  static deserialize(data: SerializedTreeState, hashFunction?: HashFunction<Element>): MerkleTree {
+    return new MerkleTree(data.levels, data._layers[0], { hashFunction, zeroElement: data._zeros[0] })
+  }
+}
+
diff --git a/src/index.ts b/src/index.ts
index 3a7c7f1..b331226 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,260 +1,15 @@
-import simpleHash from './simpleHash'
+import { simpleHash } from './simpleHash'
 
-const defaultHash = (left: Element, right: Element): string => simpleHash([left, right])
+export { default as MerkleTree } from './fixedMerkleTree'
+export { PartialMerkleTree } from './partialMerkleTree'
+export { simpleHash } from './simpleHash'
 
-export default class MerkleTree {
-  get layers(): Array<Element[]> {
-    return this._layers.slice()
-  }
-
-  set layers(value: Array<Element[]>) {
-    this._layers = value
-  }
-
-  levels: number
-  capacity: number
-  private _hashFn: HashFunction
-  private zeroElement: Element
-  private _zeros: Element[]
-  private _layers: Array<Element[]>
-
-  constructor(levels: number, elements: Element[] = [], {
-    hashFunction = defaultHash,
-    zeroElement = 0,
-  }: MerkleTreeOptions = {}) {
-    this.levels = levels
-    this.capacity = 2 ** levels
-    if (elements.length > this.capacity) {
-      throw new Error('Tree is full')
-    }
-    this._hashFn = hashFunction
-    this.zeroElement = zeroElement
-    this._zeros = []
-    this._zeros[0] = zeroElement
-    for (let i = 1; i <= levels; i++) {
-      this._zeros[i] = this._hashFn(this._zeros[i - 1], this._zeros[i - 1])
-    }
-    this._layers = []
-    this._layers[0] = elements.slice()
-    this._rebuild()
-  }
-
-  _rebuild() {
-    for (let level = 1; level <= this.levels; level++) {
-      this._layers[level] = []
-      for (let i = 0; i < Math.ceil(this._layers[level - 1].length / 2); i++) {
-        this._layers[level][i] = this._hashFn(
-          this._layers[level - 1][i * 2],
-          i * 2 + 1 < this._layers[level - 1].length
-            ? this._layers[level - 1][i * 2 + 1]
-            : this._zeros[level - 1],
-        )
-      }
-    }
-  }
-
-  /**
-   * Get tree root
-   */
-  root(): string {
-    return `${this._layers[this.levels].length > 0 ? this._layers[this.levels][0] : this._zeros[this.levels]}`
-  }
-
-  /**
-   * Insert new element into the tree
-   * @param element Element to insert
-   */
-  insert(element: Element) {
-    if (this._layers[0].length >= this.capacity) {
-      throw new Error('Tree is full')
-    }
-    this.update(this._layers[0].length, element)
-  }
-
-  /**
-   * Insert multiple elements into the tree.
-   * @param {Array} elements Elements to insert
-   */
-  bulkInsert(elements: Element[]) {
-    if (!elements.length) {
-      return
-    }
-
-    if (this._layers[0].length + elements.length > this.capacity) {
-      throw new Error('Tree is full')
-    }
-    // First we insert all elements except the last one
-    // updating only full subtree hashes (all layers where inserted element has odd index)
-    // the last element will update the full path to the root making the tree consistent again
-    for (let i = 0; i < elements.length - 1; i++) {
-      this._layers[0].push(elements[i])
-      let level = 0
-      let index = this._layers[0].length - 1
-      while (index % 2 === 1) {
-        level++
-        index >>= 1
-        this._layers[level][index] = this._hashFn(
-          this._layers[level - 1][index * 2],
-          this._layers[level - 1][index * 2 + 1],
-        )
-      }
-    }
-    this.insert(elements[elements.length - 1])
-  }
-
-  /**
-   * Change an element in the tree
-   * @param {number} index Index of element to change
-   * @param element Updated element value
-   */
-  update(index: number, element: Element) {
-    if (isNaN(Number(index)) || index < 0 || index > this._layers[0].length || index >= this.capacity) {
-      throw new Error('Insert index out of bounds: ' + index)
-    }
-    this._layers[0][index] = element
-    for (let level = 1; level <= this.levels; level++) {
-      index >>= 1
-      this._layers[level][index] = this._hashFn(
-        this._layers[level - 1][index * 2],
-        index * 2 + 1 < this._layers[level - 1].length
-          ? this._layers[level - 1][index * 2 + 1]
-          : this._zeros[level - 1],
-      )
-    }
-  }
-
-  /**
-   * Get merkle path to a leaf
-   * @param {number} index Leaf index to generate path for
-   * @returns {{pathElements: Object[], pathIndex: number[]}} An object containing adjacent elements and left-right index
-   */
-  path(index: Element): ProofPath {
-    if (isNaN(Number(index)) || index < 0 || index >= this._layers[0].length) {
-      throw new Error('Index out of bounds: ' + index)
-    }
-    let elIndex = +index
-    const pathElements: Element[] = []
-    const pathIndices: number[] = []
-    const pathPositions: number [] = []
-    for (let level = 0; level < this.levels; level++) {
-      pathIndices[level] = elIndex % 2
-      const leafIndex = elIndex ^ 1
-      if (leafIndex < this._layers[level].length) {
-        pathElements[level] = this._layers[level][leafIndex]
-        pathPositions[level] = leafIndex
-      } else {
-        pathElements[level] = this._zeros[level]
-        pathPositions[level] = 0
-      }
-      elIndex >>= 1
-    }
-    return {
-      pathElements,
-      pathIndices,
-      pathPositions,
-    }
-  }
-
-  /**
-   * Find an element in the tree
-   * @param element An element to find
-   * @param comparator A function that checks leaf value equality
-   * @returns {number} Index if element is found, otherwise -1
-   */
-  indexOf(element: Element, comparator?: <T, R> (arg0: T, arg1: T) => R): number {
-    if (comparator) {
-      return this._layers[0].findIndex((el) => comparator<Element, number>(element, el))
-    } else {
-      return this._layers[0].indexOf(element)
-    }
-  }
-
-  getTreeEdge(edgeElement: Element, index?: number) {
-    if (edgeElement === 'undefined') {
-      throw new Error('element is required')
-    }
-    let edgeIndex: number
-    if (!Number.isInteger(index)) {
-      index = -1
-      const leaves = this._layers[0]
-      index = leaves.indexOf(edgeElement)
-      edgeIndex = index
-    }
-
-    if (index <= -1) {
-      return []
-    }
-    const edgePath = this.path(index)
-    return { edgePath, edgeElement, edgeIndex }
-  }
-
-  /**
-   * Returns a copy of non-zero tree elements.
-   */
-  get elements() {
-    return this._layers[0].slice()
-  }
-
-  /**
-   * Returns a copy of n-th zero elements array
-   */
-  get zeros() {
-    return this._zeros.slice()
-  }
-
-  getLayersAsObject() {
-    const layers = this.layers
-    const objs = []
-    for (let i = 0; i < this.levels; i++) {
-      const arr = []
-      for (let j = 0; j < layers[i].length; j++) {
-        const obj = { [layers[i][j]]: null }
-        if (objs.length) {
-          obj[layers[i][j]] = {}
-          const a = objs.shift()
-          const akey = Object.keys(a)[0]
-          obj[layers[i][j]][akey] = a[akey]
-          if (objs.length) {
-            const b = objs.shift()
-            const bkey = Object.keys(b)[0]
-            obj[layers[i][j]][bkey] = b[bkey]
-          }
-        }
-        arr.push(obj)
-      }
-      objs.push(...arr)
-    }
-    return objs[0]
-  }
-
-  /**
-   * Serialize entire tree state including intermediate layers into a plain object
-   * Deserializing it back will not require to recompute any hashes
-   * Elements are not converted to a plain type, this is responsibility of the caller
-   */
-  serialize(): SerializedTreeState {
-    return {
-      levels: this.levels,
-      _zeros: this._zeros,
-      _layers: this._layers,
-    }
-  }
-
-  /**
-   * Deserialize data into a MerkleTree instance
-   * Make sure to provide the same hashFunction as was used in the source tree,
-   * otherwise the tree state will be invalid
-   */
-  static deserialize(data: SerializedTreeState, hashFunction?: HashFunction): MerkleTree {
-    return new MerkleTree(data.levels, data._layers[0], { hashFunction, zeroElement: data._zeros[0] })
-  }
+export type HashFunction<T> = {
+  (left: T, right: T): string
 }
 
-export type HashFunction = {
-  (left: string | number, right: string | number): string
-}
 export type MerkleTreeOptions = {
-  hashFunction?: HashFunction
+  hashFunction?: HashFunction<Element>
   zeroElement?: Element
 }
 
@@ -271,3 +26,9 @@ export type ProofPath = {
   pathIndices: number[],
   pathPositions: number[],
 }
+export type TreeEdge = {
+  edgeElement: Element;
+  edgePath: ProofPath;
+  edgeIndex: number
+}
+export const defaultHash = (left: Element, right: Element): string => simpleHash([left, right])
diff --git a/src/partialMerkleTree.ts b/src/partialMerkleTree.ts
index 4050b20..d5e4092 100644
--- a/src/partialMerkleTree.ts
+++ b/src/partialMerkleTree.ts
@@ -1,27 +1,31 @@
-import { Element, HashFunction, ProofPath } from './index'
+import { defaultHash, Element, HashFunction, MerkleTreeOptions, ProofPath, TreeEdge } from './'
 
 type LeafWithIndex = { index: number, data: Element }
 
 export class PartialMerkleTree {
   levels: number
-  private _hash: HashFunction
   private zeroElement: Element
   private _zeros: Element[]
   private _layers: Array<Element[]>
   private _leaves: Element[]
   private _leavesAfterEdge: Element[]
   private _edgeLeaf: LeafWithIndex
-  private _root: string
-  private _hashFn: HashFunction
+  private _root: Element
+  private _hashFn: HashFunction<Element>
   private _edgeLeafProof: ProofPath
 
-  constructor(edgeLeafProof: ProofPath, edgeLeaf: LeafWithIndex, leaves: Element[], root: string, hashFn: HashFunction) {
-    this._edgeLeafProof = edgeLeafProof
-    this._edgeLeaf = edgeLeaf
+  constructor({
+    edgePath,
+    edgeElement,
+    edgeIndex,
+  }: TreeEdge, leaves: Element[], root: Element, { hashFunction, zeroElement }: MerkleTreeOptions = {}) {
+    this._edgeLeafProof = edgePath
+    this.zeroElement = zeroElement ?? 0
+    this._edgeLeaf = { data: edgeElement, index: edgeIndex }
     this._leavesAfterEdge = leaves
     this._root = root
-    this._hashFn = hashFn
-
+    this._hashFn = hashFunction || defaultHash
+    this._buildTree()
   }
 
   get capacity() {
@@ -32,15 +36,23 @@ export class PartialMerkleTree {
     const edgeLeafIndex = this._edgeLeaf.index
     this._leaves = [...Array.from({ length: edgeLeafIndex - 1 }, () => null), ...this._leavesAfterEdge]
     this._layers = [this._leaves]
+    this._buildZeros()
     this._rebuild()
 
   }
 
+  private _buildZeros() {
+    this._zeros = [this.zeroElement]
+    for (let i = 1; i <= this.levels; i++) {
+      this._zeros[i] = this._hashFn(this._zeros[i - 1], this._zeros[i - 1])
+    }
+  }
+
   _rebuild() {
     for (let level = 1; level <= this.levels; level++) {
       this._layers[level] = []
       for (let i = 0; i < Math.ceil(this._layers[level - 1].length / 2); i++) {
-        this._layers[level][i] = this._hash(
+        this._layers[level][i] = this._hashFn(
           this._layers[level - 1][i * 2],
           i * 2 + 1 < this._layers[level - 1].length
             ? this._layers[level - 1][i * 2 + 1]
diff --git a/src/simpleHash.ts b/src/simpleHash.ts
index 9368ed9..9c56848 100644
--- a/src/simpleHash.ts
+++ b/src/simpleHash.ts
@@ -5,7 +5,7 @@
  * @param hashLength
  */
 
-function simpleHash<T>(data: T[], seed?: number, hashLength = 40): string {
+export function simpleHash<T>(data: T[], seed?: number, hashLength = 40): string {
   const str = data.join('')
   let i, l,
     hval = seed ?? 0x811c9dcc5
@@ -17,4 +17,3 @@ function simpleHash<T>(data: T[], seed?: number, hashLength = 40): string {
   return BigInt('0x' + hash.padEnd(hashLength - (hash.length - 1), '0')).toString(10)
 }
 
-export default simpleHash
diff --git a/test/merkleTree.spec.ts b/test/merkleTree.spec.ts
index 2d03e8c..94f8975 100644
--- a/test/merkleTree.spec.ts
+++ b/test/merkleTree.spec.ts
@@ -1,4 +1,4 @@
-import MerkleTree from '../src'
+import { MerkleTree } from '../src'
 import { assert, should } from 'chai'
 import { it } from 'mocha'
 
@@ -74,7 +74,7 @@ describe('MerkleTree', () => {
       should().equal(tree.root(), '4066635800770511602067209448381558554624')
     })
 
-    it('should give the same result as sequental inserts', () => {
+    it('should give the same result as sequential inserts', () => {
       const initialArray = [
         [1],
         [1, 2],
@@ -278,6 +278,24 @@ describe('MerkleTree', () => {
       const layers2 = tree.layers
       should().not.equal(layers1, layers2)
     })
+    it('should return correct zeros array', () => {
+      const zeros = [
+        0,
+        '1390935134112885103361924701261056180224',
+        '3223901263414086620636498663535535980544',
+        '938972308169430750202858820582946897920',
+        '3743880566844110745576746962917825445888',
+      ]
+      const tree = new MerkleTree(4, [])
+      assert.deepEqual(tree.zeros, zeros, 'Not equal')
+    })
+    it('should return copy of zeros array', () => {
+      const tree = new MerkleTree(4, [])
+      const zeros1 = tree.zeros
+      tree.insert(6)
+      const zeros2 = tree.zeros
+      should().not.equal(zeros1, zeros2)
+    })
   })
 
   describe('#serialize', () => {
diff --git a/test/partialMerkleTree.spec.ts b/test/partialMerkleTree.spec.ts
new file mode 100644
index 0000000..cbe9a67
--- /dev/null
+++ b/test/partialMerkleTree.spec.ts
@@ -0,0 +1,19 @@
+import { MerkleTree, PartialMerkleTree } from '../src'
+import { assert, should } from 'chai'
+import { it } from 'mocha'
+
+describe('PartialMerkleTree', () => {
+
+  describe('#constructor', () => {
+    const leaves = [1, 2, 3, 4, 5]
+    const fullTree = new MerkleTree(4, leaves)
+    const root = fullTree.root()
+    const edge = fullTree.getTreeEdge(3)
+    const leavesAfterEdge = leaves.splice(edge.edgeIndex)
+    it('should initialize merkle tree', () => {
+      const partialTree = new PartialMerkleTree(edge, leavesAfterEdge, root)
+      console.log(partialTree)
+      return true
+    })
+  })
+})
diff --git a/test/simpleHash.spec.ts b/test/simpleHash.spec.ts
index 39fbb2a..2bd6ad1 100644
--- a/test/simpleHash.spec.ts
+++ b/test/simpleHash.spec.ts
@@ -1,4 +1,4 @@
-import simpleHash from '../src/simpleHash'
+import { simpleHash } from '../src'
 import { it } from 'mocha'
 import { should } from 'chai'