166th Commit

src/page-22/2325. Decode the Message/decodeMessage.test.ts

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+import { decodeMessage } from './decodeMessage';
+
+describe('2325. Decode the Message', () => {
+  test('decodeMessage', () => {
+    {
+      const key = 'the quick brown fox jumps over the lazy dog';
+      const message = 'vkbs bs t suepuv';
+      const expected = 'this is a secret';
+      expect(decodeMessage(key, message)).toBe(expected);
+    }
+
+    {
+      const key = 'eljuxhpwnyrdgtqkviszcfmabo';
+      const message = 'zwx hnfx lqantp mnoeius ycgk vcnjrdb';
+      const expected = 'the five boxing wizards jump quickly';
+      expect(decodeMessage(key, message)).toBe(expected);
+    }
+  });
+});

src/page-22/2325. Decode the Message/decodeMessage.ts

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+type DecodeMessage = (key: string, message: string) => string;
+
+/**
+ * Accepted
+ */
+export const decodeMessage: DecodeMessage = (key, message) => {
+  // Create a Map to store the substitution table
+  const substitutionMap = new Map<string, string>();
+
+  // Define the regular English alphabet
+  const alphabet = 'abcdefghijklmnopqrstuvwxyz';
+
+  // Variable to keep track of the current index in the alphabet
+  let substitutionIndex = 0;
+
+  // Loop through each character in the key string
+  for (const char of key) {
+    // Check if the character is a lowercase English letter and is not already in the map
+    if (char >= 'a' && char <= 'z' && !substitutionMap.has(char)) {
+      // Add the character to the map with its corresponding letter in the alphabet
+      substitutionMap.set(char, alphabet[substitutionIndex]);
+
+      // Move to the next letter in the alphabet
+      substitutionIndex += 1;
+    }
+  }
+
+  // Variable to store the decoded message
+  let decodedMessage = '';
+
+  // Loop through each character in the message string
+  for (const char of message) {
+    // If the character is a space, add a space to the decoded message
+    if (char === ' ') {
+      decodedMessage += ' ';
+    } else {
+      // Otherwise, substitute the character using the map and add it to the decoded message
+      decodedMessage += substitutionMap.get(char) || char;
+    }
+  }
+
+  // Return the decoded message
+  return decodedMessage;
+};