add: replacing-with-the-cipher-letters

Author: supercodestart

README.md

@@ -3,3 +3,4 @@
 - [Filling all the missed angle brackets](filling-all-the-missed-angle-brackets)
 - [Finding all the anagrams](finding-all-the-anagrams)
 - [Finding the maximum depth of a binary tree](finding-the-maximum-depth-of-a-binary-tree)
+- [Replacing with the cipher letters](replacing-with-the-cipher-letters)

replacing-with-the-cipher-letters/README.md

@@ -0,0 +1,24 @@
+# Replacing with the cipher letters
+
+- The plain and cipher letters should be lowercase(a-z).
+- The plain letter should be replaced with the cipher letter of same position.
+
+e.g.
+
+Input
+
+```console
+helloworld
+```
+
+Output
+
+```console
+svooldliow
+```
+
+## Execute
+
+```bash
+node solution.js
+```

replacing-with-the-cipher-letters/solution.js

@@ -0,0 +1,26 @@
+const solution = (word, cipher) => {
+  if (
+    !/^[a-z]+$/.test(word) ||
+    !word ||
+    !cipher ||
+    cipher.length !== 26
+  ) {
+    return '';
+  }
+  let result = '';
+  const aCode = 'a'.charCodeAt(0);
+  for (let i = 0; i < word.length; i++) {
+    const index = word.charCodeAt(i) - aCode;
+    if (index < 0 || index >= cipher.length) {
+      continue;
+    }
+    result += cipher.charAt(index);
+  }
+  return result;
+};
+
+(() => {
+  console.log(
+    solution('helloworld', 'zyxwvutsrqponmlkjihgfedcba'),
+  );
+})();