license key formatting

Author: rohan-paul

solutions/2-sum.js renamed to 2-sum.js

@@ -0,0 +1,67 @@
+/* // https://leetcode.com/problems/license-key-formatting/description/
+
+You are given a license key represented as a string S which consists only alphanumeric character and dashes. The string is separated into N+1 groups by N dashes.
+
+Rule - Given a number K, we would want to reformat the strings such that each group contains exactly K characters, except for the first group which could be shorter than K, but still must contain at least one character. Furthermore, there must be a dash inserted between two groups and all lowercase letters should be converted to uppercase.
+
+Given a non-empty string S and a number K, format the string according to the rules described above.
+
+Example 1:
+Input: S = "5F3Z-2e-9-w", K = 4
+
+Output: "5F3Z-2E9W"
+
+Explanation: The string S has been split into two parts, each part has 4 characters.
+Note that the two extra dashes are not needed and can be removed.
+Example 2:
+Input: S = "2-5g-3-J", K = 2
+
+Output: "2-5G-3J"
+
+Explanation: The string S has been split into three parts, each part has 2 characters except the first part as it could be shorter as mentioned above. */
+
+/* Algo -
+
+A) Replace all the "-" from the given string with empty space, so I am left with a clean alpha-numeric string
+
+B) Looking at the above input example, Length of the first group will have K elements ONLY if len is divisible by K .
+
+C) And if len is NOT divisible then make the length of the first group to be equal to the remainder (of len / K ) - so the rest of the group can each take K letters.
+
+D) Now use substring() to form the first group - by extracting letters from 0-index upto length-of-first-group - 1. Meaning if ength-of-first-group is 4, I have to extract upto 3. And substring() by definition works like that. It does not include the indexEnd (its second argument )
+
+str.substring(indexStart[, indexEnd]) - substring() extracts characters from indexStart up to but not including indexEnd
+
+indexStart - The index of the first character to include in the returned substring.
+indexEnd - Optional. The index of the first character to exclude from the returned substring.
+Return value - A new string containing the specified part of the given string.
+
+*/
+
+var licenseKeyFormatting = function(S, K) {
+
+    let cleanStr = S.toUpperCase().replace(/-/g, '');
+
+    let len = cleanStr.length;
+
+    // let s1 is the length of the first group
+
+    let s1 = (( len % K ) === 0 ) ? K :  (len % K);
+
+    // now form the first group of the resultant string
+    let resultStr = cleanStr.substring(0, s1);
+
+    // Now that, I have the first group, the next group will be >> first-group + "-" + K elements of the string
+    // Also as a final reconciliation after I place all the K number of elements in each group the total length should be equal to cleanStr length
+    // i.e. s1 + K + K ... === len  . Till this is not the case, I have to keep placing each K elements to each group
+
+    while (len > s1 ) {
+        resultStr += "-" + cleanStr.substring(s1, s1 + K)
+        s1 += K
+    }
+    return resultStr;
+};
+
+console.log(licenseKeyFormatting("5F3Z-2e-9-w", 4))  // => 5F3Z-2E9W
+
+console.log(licenseKeyFormatting("2-5g-3-J", 2))  // => "2-5G-3J"

solutions/Max_Average_Subarray-2.js renamed to Max_Average_Subarray-2.js

@@ -33,6 +33,7 @@ var reverse = function(x) {
 
 // // SOLUTION-2 - Best Performing solution. And also if the Problems asks for not to use any string related methods.
 var reverseBest = function(x) {
+
 	var y = Math.abs(x);
 	var result = 0;
 
@@ -109,4 +110,6 @@ const reverseNum = x => {
 
 console.log(reverseNum(123)); // => 321
 console.log(reverseNum(-123)); // => -321
-console.log(reverseNum( 1534236469 )) // => 0
+console.log(reverseNum( 1534236469 )) // => 0
+
+/* split() is a string’s prototype method that converts a string to an array. Providing an empty string as an argument means split by each character. So the resulting array would have each character as an element of the array. */