Add a simple hash algorithm

Author: FSou1

src/algorithms/cryptography/polynomial-hash/README.md

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+# Polynomial Rolling Hash
+
+## Simple hash
+
+**Time complexity**: `O(n)`, where n is the size of the string
+
+## Rolling hash
+
+**Time complexity**: `O(1)`.
+
+## Reference
+
+- [Youtube](https://www.youtube.com/watch?v=w6nuXg0BISo);
+- [Wikipedia](https://en.wikipedia.org/wiki/Rolling_hash);

src/algorithms/cryptography/polynomial-hash/__tests__/simpleHash.test.ts

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+import {SimpleHasher} from '../simpleHash';
+
+test.each([
+  [null, 0],
+  [undefined, 0],
+  ['', 0],
+  ['a', 97],
+  [' a', 2263],
+  ['ab', 2351],
+  ['abc', 54722],
+  ['bcz', 66913],
+])('a hash representation of %p is %p', (word, hash) => {
+  const hasher = new SimpleHasher();
+  expect(hasher.hash(word)).toBe(hash);
+});
+
+test.each([
+  [97, 'a', 'b', 98],
+  [2263, ' a', 'ab', 2351],
+  [54722, 'abc', 'bcz', 66913],
+])('a rolled hash from %p of %p to %p is %p', (pHash, pWord, nWord, nHash) => {
+  const hasher = new SimpleHasher();
+  expect(hasher.roll(pHash, pWord, nWord)).toBe(nHash);
+});

src/algorithms/cryptography/polynomial-hash/simpleHash.ts

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+const DEFAULT_BASE = 23;
+
+/**
+ * Simple polynomial hash
+ *
+ * @export
+ * @class SimpleHasher
+ */
+export class SimpleHasher {
+  base: number;
+
+  /**
+   *Creates an instance of SimpleHasher
+   * @param {*} [base=DEFAULT_BASE]
+   * @memberof SimpleHasher
+   */
+  constructor(base = DEFAULT_BASE) {
+    this.base = base;
+  }
+
+  /**
+   * Creates a hash representation of the word
+   *
+   * @param {string} word
+   * @return {number}
+   * @memberof SimpleHasher
+   */
+  hash(word: string): number {
+    if (!word) {
+      return 0;
+    }
+
+    let hash = 0;
+
+    for (let charIndex = 0; charIndex < word.length; charIndex += 1) {
+      hash += word.charCodeAt(charIndex) * (this.base ** charIndex);
+    }
+
+    return hash;
+  }
+
+  /**
+   * Creates hash representation of the word based on
+   * previous word (shifted by one character left) hash value
+   *
+   * @param {number} prevHash
+   * @param {string} prevWord
+   * @param {string} newWord
+   * @return {number}
+   * @memberof SimpleHasher
+   */
+  roll(prevHash: number, prevWord: string, newWord: string): number {
+    let hash = prevHash;
+
+    const prevValue = prevWord.charCodeAt(0);
+    const newValue = newWord.charCodeAt(newWord.length - 1);
+
+    hash -= prevValue;
+    hash /= this.base;
+    hash += newValue * (this.base ** (newWord.length - 1));
+
+    return hash;
+  }
+}