Create Reverse_String_II.js

Author: ignacio-chiazzo

LeetcodeProblems/Reverse_String_II.js

@@ -0,0 +1,49 @@
+/*
+
+Reverse String II
+
+https://leetcode.com/problems/reverse-string-ii/description/
+
+Given a string and an integer k, you need to reverse the first k characters for every 2k characters counting from the start of the string. If there are less than k characters left, reverse all of them. If there are less than 2k but greater than or equal to k characters, then reverse the first k characters and left the other as original.
+Example:
+Input: s = "abcdefg", k = 2
+Output: "bacdfeg"
+Restrictions:
+The string consists of lower English letters only.
+Length of the given string and k will in the range [1, 10000]
+*/
+var reverseStr = function(s, k) {
+  if(k <= 1)
+    return s;
+  var ret = "";
+  for(var iterK = 0; iterK * k < s.length; iterK = iterK + 2) {
+      const start = iterK * k;
+      const end = start + k - 1; 
+    
+      ret += reverse(s, start, end);
+      ret += s.slice(end + 1, k * (iterK + 2)); 
+  }
+  
+  return ret;
+};
+
+var reverse = function(s, start, end) {
+  var ret = "";
+  if(end >= s.length)
+      end = s.length - 1;
+  
+  while(start <= end) {
+      ret += s.charAt(end);
+      end--;
+  }
+  return ret;
+}
+
+var main = function(){
+  console.log(reverseStr("abcdefg", 2));
+  console.log(reverseStr("abcdefg", 3));
+  console.log(reverseStr("abcdefg", 1));
+  console.log(reverseStr("abcdefg", 0));  
+}
+
+module.exports.main = main