Refactored grains to use bigint in the example and tests. Also left a note to use bigint in the problem description

Author: joshiraez

exercises/practice/grains/.docs/instructions.md

@@ -16,6 +16,8 @@ Write code that shows:
 - how many grains were on a given square, and
 - the total number of grains on the chessboard
 
+You will need to use the [bigint](https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-2.html#bigint) type in this problem, as the usual `number` type loses precision when on big numbers, being a floating point based storage.
+
 ## For bonus points
 
 Did you get the tests passing and the code clean? If you want to, these

exercises/practice/grains/.meta/proof.ci.ts

@@ -1,16 +1,16 @@
-export function square(square: number): number {
+export function square(square: number): bigint {
   if (square <= 0 || square >= 65) {
     throw new Error()
   }
 
-  return Math.pow(2, square - 1)
+  return BigInt(square) ** 2n
 }
 
-export function total(): number {
-  let total = 0
+export function total(): bigint {
+  let total = 0n
 
   for (let i = 1; i <= 64; i++) {
-    total += square(i)
+    total += this.square(i)
   }
 
   return total

exercises/practice/grains/grains.test.ts

@@ -2,37 +2,37 @@ import { square, total } from './grains'
 
 describe('returns the number of grains on the square', () => {
   it('1', () => {
-    const expected = 1
+    const expected = 1n
     expect(square(1)).toEqual(expected)
   })
 
   xit('2', () => {
-    const expected = 2
+    const expected = 2n
     expect(square(2)).toEqual(expected)
   })
 
   xit('3', () => {
-    const expected = 4
+    const expected = 4n
     expect(square(3)).toEqual(expected)
   })
 
   xit('4', () => {
-    const expected = 8
+    const expected = 8n
     expect(square(4)).toEqual(expected)
   })
 
   xit('16', () => {
-    const expected = 32768
+    const expected = 32768n
     expect(square(16)).toEqual(expected)
   })
 
   xit('32', () => {
-    const expected = 2147483648
+    const expected = 2147483648n
     expect(square(32)).toEqual(expected)
   })
 
   xit('64', () => {
-    const expected = 9223372036854775808
+    const expected = 9223372036854775808n
     expect(square(64)).toEqual(expected)
   })
 
@@ -51,7 +51,7 @@ describe('returns the number of grains on the square', () => {
 
 describe('returns the total number of grains on the board', () => {
   xit('total', () => {
-    const expected = 18446744073709551615
+    const expected = 18446744073709551615n
     expect(total()).toEqual(expected)
   })
 })

exercises/practice/grains/tsconfig.json

@@ -1,7 +1,7 @@
 {
   "compilerOptions": {
     /* Basic Options */
-    "target": "es2017" /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017','ES2018' or 'ESNEXT'. */,
+    "target": "esnext" /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017','ES2018' or 'ESNEXT'. */,
     "module": "commonjs" /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', or 'ESNext'. */,
     "lib": [
       "esnext",

tsconfig.json

@@ -63,5 +63,5 @@
     // "emitDecoratorMetadata": true,         /* Enables experimental support for emitting type metadata for decorators. */
   },
   "compileOnSave": true,
-  "exclude": ["node_modules"]
+  "exclude": ["node_modules", "exercises"]
 }