Merge pull request #481 from sir-gon/feature/frequency_queries

Feature/frequency queries

Author: sir-gon

src/hackerrank/interview_preparation_kit/dictionaries_and_hashmaps/frequency_queries.js

@@ -2,43 +2,78 @@
  * @link Problem definition [[docs/hackerrank/interview_preparation_kit/dictionaries_and_hashmaps/frequency-queries.md]]
  */
 
-// Complete the freqQuery function below.
+export function updateFrequency(frequencyMap, data, currentFreq, newFreq) {
+  const freqMap = frequencyMap;
+
+  if (newFreq > 0) {
+    if (freqMap?.[newFreq]) {
+      freqMap[newFreq].push(data);
+    } else {
+      freqMap[newFreq] = [data];
+    }
+  }
+
+  if (freqMap?.[currentFreq]) {
+    freqMap[currentFreq] = freqMap[currentFreq].filter((f) => f !== data);
+
+    if (freqMap[currentFreq].length === 0) {
+      delete freqMap?.[currentFreq];
+    }
+  }
+
+  return freqMap;
+}
+
 export function freqQuery(queries) {
   const result = [];
   const dataMap = {};
+  const freqMap = {};
 
   const __INITIAL__ = 0;
   const __INSERT__ = 1;
   const __DELETE__ = 2;
   const __SELECT__ = 3;
 
+  const __NOT_FOUND__ = 0;
+  const __FOUND__ = 1;
+
   queries.forEach((query) => {
     const [operation, data] = query;
 
-    const current = dataMap?.[data] ?? __INITIAL__;
+    const currentFreq = dataMap?.[data] ?? __INITIAL__;
+    let newFreq = currentFreq + 1;
 
     switch (operation) {
       case __INSERT__:
-        dataMap[data] = current + 1;
+        // map of values
+        dataMap[data] = currentFreq + 1;
+
+        // map of frequencies
+        newFreq = currentFreq + 1;
         break;
       case __DELETE__:
-        dataMap[data] = Math.max(0, current - 1);
+        // map of values
+        dataMap[data] = Math.max(0, currentFreq - 1);
+
+        // map of frequencies
+        newFreq = currentFreq - 1;
+
         break;
-      case __SELECT__:
-        for (const [key, value] of Object.entries(dataMap)) {
-          console.log(key, value);
-          if (value === data) {
-            result.push(1);
-            break;
-          }
-        }
-        if (result.length === 0) {
-          result.push(0);
+      case __SELECT__: {
+        if (freqMap?.[data]) {
+          result.push(__FOUND__);
+        } else {
+          result.push(__NOT_FOUND__);
         }
         break;
+      }
       default:
         throw new Error('Invalid operation');
     }
+
+    if (operation === __INSERT__ || operation === __DELETE__) {
+      updateFrequency(freqMap, data, currentFreq, newFreq);
+    }
   });
 
   return result;

src/hackerrank/interview_preparation_kit/dictionaries_and_hashmaps/frequency_queries.test.js

@@ -17,17 +17,69 @@ const TEST_CASES = [
       [3, 2]
     ],
     expected: [0, 1]
+  },
+  {
+    title: 'Sample Test Case 1',
+    input: [
+      [3, 4],
+      [2, 1003],
+      [1, 16],
+      [3, 1]
+    ],
+    expected: [0, 1]
+  },
+  {
+    title: 'Sample Test Case 2',
+    input: [
+      [1, 3],
+      [2, 3],
+      [3, 2],
+      [1, 4],
+      [1, 5],
+      [1, 5],
+      [1, 4],
+      [3, 2],
+      [2, 4],
+      [3, 2]
+    ],
+    expected: [0, 1, 1]
+  },
+  {
+    title: 'Sample Test Case 3',
+    input: [
+      [1, 3],
+      [1, 38],
+      [2, 1],
+      [1, 16],
+      [2, 1],
+      [2, 2],
+      [1, 64],
+      [1, 84],
+      [3, 1],
+      [1, 100],
+      [1, 10],
+      [2, 2],
+      [2, 1],
+      [1, 67],
+      [2, 2],
+      [3, 1],
+      [1, 99],
+      [1, 32],
+      [1, 58],
+      [3, 2]
+    ],
+    expected: [1, 1, 0]
   }
 ];
 
 describe('frequency_queries', () => {
   it('freqQuery test cases', () => {
-    expect.assertions(1);
+    expect.assertions(4);
 
     TEST_CASES.forEach((value) => {
       const answer = freqQuery(value.input);
 
-      console.debug(`checkMagazine(${value.input}) solution found: ${answer}`);
+      console.debug(`freqQuery(${value.input}) solution found: ${answer}`);
 
       expect(answer).toStrictEqual(value.expected);
     });