[BUGFIX] [Hacker Rank] Interview Preparation Kit: Dynamic Programming: Max Array Sum. FIXED ✅.

* BigInt required for big cases
* New test case added
* Test cases data moved to JSON.

Author: Gonzalo Diaz

src/hackerrank/interview_preparation_kit/dynamic_programming/max_array_sum.test.ts

@@ -3,30 +3,19 @@ import { logger as console } from '../../../logger';
 
 import { maxSubsetSum } from './max_array_sum';
 
-const TEST_CASES = [
-  {
-    title: 'Sample Test case 0',
-    input: [3, 7, 4, 6, 5],
-    expected: 13
-  },
-  {
-    title: 'Sample Test case 1',
-    input: [2, 1, 5, 8, 4],
-    expected: 11
-  },
-  {
-    title: 'Sample Test case 2',
-    input: [3, 5, -7, 8, 10],
-    expected: 15
-  }
-];
+import TEST_CASES from './max_array_sum.testcases.json';
+import TEST_CASE3 from './max_array_sum.testcase3.json';
+
+const ALL_TEST_CASES = [...TEST_CASES, TEST_CASE3];
+
+const DECIMAL_RADIX = 10;
 
 describe('max_array_sum', () => {
   it('maxSubsetSum test cases', () => {
-    expect.assertions(3);
+    expect.assertions(4);
 
-    TEST_CASES.forEach((test) => {
-      const answer = maxSubsetSum(test.input);
+    ALL_TEST_CASES.forEach((test) => {
+      const answer = maxSubsetSum(test.input).toString(DECIMAL_RADIX);
 
       console.debug(`maxSubsetSum(${test.input}) solution found: ${answer}`);
 

src/hackerrank/interview_preparation_kit/dynamic_programming/max_array_sum.testcase3.json

@@ -0,0 +1,17 @@
+[
+  {
+    "title": "Sample Test case 0",
+    "input": [3, 7, 4, 6, 5],
+    "expected": "13"
+  },
+  {
+    "title": "Sample Test case 1",
+    "input": [2, 1, 5, 8, 4],
+    "expected": "11"
+  },
+  {
+    "title": "Sample Test case 2",
+    "input": [3, 5, -7, 8, 10],
+    "expected": "15"
+  }
+]

src/hackerrank/interview_preparation_kit/dynamic_programming/max_array_sum.testcases.json

@@ -3,8 +3,11 @@
  * @see Solution Notes: [[docs/hackerrank/interview_preparation_kit/dynamic_programming/max_array_sum-solution-notes.md]]
  */
 
+const bigIntMax = (...args: bigint[]): bigint =>
+  args.reduce((m, e) => (e > m ? e : m), BigInt(0));
+
 export function maxSubsetSum(arr: number[]): number {
-  const arrCopy = [...arr];
+  const arrCopy: bigint[] = arr.map((x: number): bigint => BigInt(x));
 
   if (arrCopy.length == 0) {
     return 0;
@@ -13,19 +16,19 @@ export function maxSubsetSum(arr: number[]): number {
   const total = arrCopy.length;
 
   if (total == 1) {
-    return arrCopy[0];
+    return Number(arrCopy[0]);
   }
 
-  let t_max = Math.max(arrCopy[0], arrCopy[1]);
+  let t_max = bigIntMax(arrCopy[0], arrCopy[1]);
   arrCopy[1] = t_max;
 
   for (let i = 2; i < total; i++) {
-    t_max = Math.max(arr[i - 2] + arr[i], t_max);
-    t_max = Math.max(arr[i], t_max);
-    arr[i] = t_max;
+    t_max = bigIntMax(arrCopy[i - 2] + arrCopy[i], t_max);
+    t_max = bigIntMax(arrCopy[i], t_max);
+    arrCopy[i] = t_max;
   }
 
-  return t_max;
+  return Number(t_max);
 }
 
 export default { maxSubsetSum };