Feat | Interview | #7 Concat Sources Blocks: Global Type And Title

README.md

@@ -122,4 +122,5 @@ Interview Questions
 - [Task #3](src/interview/create-message-handler) - _Create Message Handler_
 - [Task #4](src/interview/create-channel-message-handler) - _Create Channel Message Handler_
 - [Task #5](src/interview/create-smart-fetch) - _Create Smart Fetch_
-- [Task #6](src/interview/time-limited-cache) - _Time Limited Cache_
+- [Task #6](src/interview/time-limited-cache) - _Time Limited Cache_
+- [Task #7](src/interview/concat-sources-blocks/global-type-and-title) - _Concat Sources Blocks: Global Type & Title_

src/interview/concat-sources-blocks/common.ts

@@ -0,0 +1,4 @@
+export interface Block {
+  type: string;
+  title: string;
+}

src/interview/concat-sources-blocks/global-type-and-title/solution.test.ts

@@ -0,0 +1,22 @@
+import { concatSourcesBlocks } from './solution';
+
+describe('Concat Sources Blocks: Global Type & Title | Interview | Testcases', () => {
+  test('#1', () => {
+    const primary = [
+      { type: 'спорт', title: 'Матч' },
+      { type: 'экономика', title: 'Курс валют' },
+    ];
+    const secondary = [
+      { type: 'политика', title: 'Главная новость' },
+      { type: 'культура', title: 'Главная новость' },
+    ];
+    const orders = ['экономика', 'политика', 'культура', 'спорт'];
+    const result = concatSourcesBlocks(primary, secondary, orders);
+    const expected = [
+      { type: 'экономика', title: 'Курс валют' },
+      { type: 'политика', title: 'Главная новость' },
+      { type: 'спорт', title: 'Матч' },
+    ];
+    expect(result).toEqual(expected);
+  });
+});

src/interview/concat-sources-blocks/global-type-and-title/solution.ts

@@ -0,0 +1,56 @@
+import { Block } from '../common';
+
+/**
+ * @param primaryBlocks - blocks from main source
+ * @param secondaryBlocks - blocks from secondary sources
+ * @param orders - requested types in order
+ * @returns array of blocks, ordered by `orders`, without repeats in `types `or `titles`.
+ * Primary blocks are in priority.
+ */
+export const concatSourcesBlocks = (
+  primaryBlocks: Block[],
+  secondaryBlocks: Block[],
+  orders: string[],
+): Block[] => {
+  const result: Block[] = [];
+  const usedTitles = new Set<string>();
+  const usedTypes = new Set<string>();
+
+  const groupByType = (blocks: Block[]): Map<string, Set<Block>> => {
+    const map = new Map<string, Set<Block>>();
+    for (const block of blocks) {
+      const group = map.get(block.type) ?? new Set<Block>();
+      group.add(block);
+      map.set(block.type, group);
+    }
+    return map;
+  };
+
+  const primaryMap = groupByType(primaryBlocks);
+  const secondaryMap = groupByType(secondaryBlocks);
+
+  const tryToAdd = (blocks: Set<Block> | undefined): boolean => {
+    if (!blocks) {
+      return false;
+    }
+    for (const block of blocks) {
+      if (!usedTitles.has(block.title) && !usedTypes.has(block.type)) {
+        result.push(block);
+        usedTypes.add(block.type);
+        usedTitles.add(block.title);
+        blocks.delete(block);
+        return true;
+      }
+      blocks.delete(block);
+    }
+    return false;
+  };
+
+  for (const order of orders) {
+    if (!tryToAdd(primaryMap.get(order))) {
+      tryToAdd(secondaryMap.get(order));
+    }
+  }
+
+  return result;
+};