[Hacker Rank] Interview Preparation Kit: Hash Tables: Ice Cream Parlo…

…r. Optimized solution ✅.

src/hackerrank/interview_preparation_kit/search/ctci_ice_cream_parlor.border_testcases.json

@@ -5,7 +5,7 @@
       {
         "costs": [1, 4, 5, 3, 2],
         "money": 90,
-        "expected": null
+        "expected": []
       }
     ]
   }

src/hackerrank/interview_preparation_kit/search/ctci_ice_cream_parlor.ts

@@ -2,25 +2,46 @@
  * @link Problem definition [[docs/hackerrank/interview_preparation_kit/search/ctci-ice-cream-parlor.md]]
  */
 
-export function whatFlavorsCompute(
-  cost: number[],
-  money: number
-): number[] | null {
-  const cache: Record<number, number> = {};
-
-  for (const [key, price] of Object.entries(cost)) {
-    const i = parseInt(key);
-    const diff = money - price;
-    const cacheKeys = new Set(Object.keys(cache));
-
-    if (cacheKeys.has(diff.toString())) {
-      return [i + 1, cache[diff] + 1].sort((a, b) => a - b);
+export function whatFlavorsCompute(cost: number[], money: number): number[] {
+  let ans1;
+  let ans2;
+
+  const CACHE: Record<number, number> = {};
+
+  for (const price of cost) {
+    CACHE[price] = Number.isInteger(CACHE[price]) ? CACHE[price] + 1 : 1;
+  }
+
+  for (const i in cost) {
+    const v1 = cost[i];
+    const v2 = money - v1;
+
+    if (v1 != v2) {
+      if (CACHE?.[v1] && CACHE?.[v2]) {
+        ans1 = v1;
+        ans2 = v2;
+        break;
+      }
+    } else {
+      // count of the element must be greater than 1 if they are same
+      if (CACHE?.[v1] && CACHE[v1] > 1) {
+        ans1 = v1;
+        ans2 = v1;
+        break;
+      }
     }
+  }
 
-    cache[price] = i;
+  const result: number[] = [];
+  for (const i in cost) {
+    const x: number = parseInt(i);
+
+    if (cost[x] == ans1 || cost[x] == ans2) {
+      result.push(x + 1);
+    }
   }
 
-  return null;
+  return result;
 }
 
 export function whatFlavors(cost: number[], money: number): void {

src/hackerrank/interview_preparation_kit/search/ctci_ice_cream_parlor_bruteforce.ts

@@ -5,7 +5,7 @@
 export function what_flavors_bruteforce_compute(
   cost: number[],
   money: number
-): number[] | null {
+): number[] {
   for (const _i in cost) {
     const i: number = parseInt(_i);
     const x: number = cost[i];
@@ -20,7 +20,7 @@ export function what_flavors_bruteforce_compute(
     }
   }
 
-  return null;
+  return [];
 }
 
 export function whatFlavors(cost: number[], money: number): void {