From f379475723b524f1ef3c1e3d06efcd4e6bcb04d9 Mon Sep 17 00:00:00 2001
From: YATIN KATHURIA <47096348+Yatin-kathuria@users.noreply.github.com>
Date: Sat, 20 Nov 2021 09:43:27 +0530
Subject: [PATCH] merge: Add TribonacciNumber in dp (#839)

---
 Dynamic-Programming/TribonacciNumber.js       | 20 ++++++++++++++++
 .../tests/TribonacciNumber.test.js            | 23 +++++++++++++++++++
 2 files changed, 43 insertions(+)
 create mode 100644 Dynamic-Programming/TribonacciNumber.js
 create mode 100644 Dynamic-Programming/tests/TribonacciNumber.test.js

diff --git a/Dynamic-Programming/TribonacciNumber.js b/Dynamic-Programming/TribonacciNumber.js
new file mode 100644
index 000000000..67a95a0e4
--- /dev/null
+++ b/Dynamic-Programming/TribonacciNumber.js
@@ -0,0 +1,20 @@
+/**
+ * @function Tribonacci
+ * @description Tribonacci is the sum of previous three tribonacci numbers.
+ * @param {Integer} n - The input integer
+ * @return {Integer} tribonacci of n.
+ * @see [Tribonacci_Numbers](https://www.geeksforgeeks.org/tribonacci-numbers/)
+ */
+const tribonacci = (n) => {
+  // creating array to store previous tribonacci numbers
+  const dp = new Array(n + 1)
+  dp[0] = 0
+  dp[1] = 1
+  dp[2] = 1
+  for (let i = 3; i <= n; i++) {
+    dp[i] = dp[i - 1] + dp[i - 2] + dp[i - 3]
+  }
+  return dp[n]
+}
+
+export { tribonacci }
diff --git a/Dynamic-Programming/tests/TribonacciNumber.test.js b/Dynamic-Programming/tests/TribonacciNumber.test.js
new file mode 100644
index 000000000..1ce012dfe
--- /dev/null
+++ b/Dynamic-Programming/tests/TribonacciNumber.test.js
@@ -0,0 +1,23 @@
+import { tribonacci } from '../TribonacciNumber'
+
+describe('TribonacciNumber', () => {
+  it('tribonacci of 0', () => {
+    expect(tribonacci(0)).toBe(0)
+  })
+
+  it('tribonacci of 1', () => {
+    expect(tribonacci(1)).toBe(1)
+  })
+
+  it('tribonacci of 2', () => {
+    expect(tribonacci(2)).toBe(1)
+  })
+
+  it('tribonacci of 10', () => {
+    expect(tribonacci(10)).toBe(149)
+  })
+
+  it('tribonacci of 25', () => {
+    expect(tribonacci(25)).toBe(1389537)
+  })
+})