Update README.md

Author: skjha1

README.md

@@ -3,23 +3,23 @@
 “A data structure is a way to store and organize data in a computer, so that it can be used efficiently.”
 ## Data Structures
 * [:blue_book:](https://drive.google.com/file/d/1wqMgL_6w8nWgFCHYXQ0NA8Kjz8LLcmKu/view?usp=sharing) [ Recursion ](https://github.com/skjha1/Data-Structure-Algorithm/tree/master/Recursion/)
-  - [Head Recursion](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/02%20head%20recursion.cpp)
-  - [Tail Recursion](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/01%20tail%20recursion.cpp)
-  - [Global variable recursion](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/03%20global%20variable%20recursion)
-  - [Static variable reciursion](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/04%20static%20variable%20in%20reciursion.c)
-  - [Tree recursion](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/05%20Tree%20recursion.c)
-  - [Nested recursion](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/06%20nested%20recursion.c)
-  - [Sum of n number using recursion](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/07%20Sum%20of%20n%20number%20using%20recursion.c)
-  - [Sum Of given number using loop](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/09%20Sum%20Of%20given%20number%20using%20loop.c)
-  - [Power using recursion](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/10%20powe%20using%20recursion.cpp)
-  - [Taylor Series using Static variables](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/12%20Taylor%20Series%20using%20Static%20variables.cpp)
-  - [Taylor Serie honers rule](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/13%20Taylor%20Serie%20honers%20rule.c)
-  - [Taylor Serie Iterative](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/14%20Taylor%20Serie%20Iterative.cpp)
-  - [Indirect Recursion](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/15%20Indirect%20Recursion.c)
-  - [Fibbonaci series using loop and recursion](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/16%20Fibbonaci%20series%20using%20loop%20and%20recursion%20.c)
-  - [Fibbonacci using memoization](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/17%20fibbonacci%20using%20memoization.c)
-  - [nCr formula](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/18%20nCr%20formula.c)
-  - [Tower of Hanoi](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/19%20Tower%20of%20Hanoi%20.c)
+  - [01 Head Recursion](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/02%20head%20recursion.cpp)
+  - [02 Tail Recursion](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/01%20tail%20recursion.cpp)
+  - [03 Global variable recursion](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/03%20global%20variable%20recursion)
+  - [04 Static variable reciursion](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/04%20static%20variable%20in%20reciursion.c)
+  - [05 Tree recursion](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/05%20Tree%20recursion.c)
+  - [06 Nested recursion](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/06%20nested%20recursion.c)
+  - [07 Sum of n number using recursion](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/07%20Sum%20of%20n%20number%20using%20recursion.c)
+  - [08 Sum Of given number using loop](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/09%20Sum%20Of%20given%20number%20using%20loop.c)
+  - [09 Power using recursion](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/10%20powe%20using%20recursion.cpp)
+  - [10 Taylor Series using Static variables](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/12%20Taylor%20Series%20using%20Static%20variables.cpp)
+  - [11 Taylor Serie honers rule](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/13%20Taylor%20Serie%20honers%20rule.c)
+  - [12 Taylor Serie Iterative](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/14%20Taylor%20Serie%20Iterative.cpp)
+  - [13 Indirect Recursion](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/15%20Indirect%20Recursion.c)
+  - [14 Fibbonaci series using loop and recursion](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/16%20Fibbonaci%20series%20using%20loop%20and%20recursion%20.c)
+  - [15 Fibbonacci using memoization](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/17%20fibbonacci%20using%20memoization.c)
+  - [16 nCr formula](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/18%20nCr%20formula.c)
+  - [17 Tower of Hanoi](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Recursion/19%20Tower%20of%20Hanoi%20.c)
 
 * [:blue_book:](https://drive.google.com/drive/folders/1VzrX63lw2w44Vr3WL8udBO5Cyc3-W5vc) [Array](https://github.com/skjha1/Data-Structure-Algorithm/tree/master/Array)
   - [01 static and dynamic array](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Array/01%20static%20and%20dynamic%20array%20.c)
@@ -53,6 +53,14 @@
   - [29 Find a pair with sum k using Hashing](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Array/29%20Find%20a%20pair%20with%20sum%20k%20using%20Hashing.cpp)
   - [30 Finding max & min in single scan](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/Array/30%20Finding%20max%20%26%20min%20in%20single%20scan.cpp)
       - [Problems on array](https://github.com/skjha1/Data-Structure-Algorithm/tree/master/Array/Problems)
+* [:blue_book:](https://drive.google.com/drive/folders/1VzrX63lw2w44Vr3WL8udBO5Cyc3-W5vc) [String](https://github.com/skjha1/Data-Structure-Algorithm/tree/master/String)
+   - [01 Length of string](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/String/01%20Length%20of%20string.cpp)
+   - [02 Upper to Lower](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/String/02%20Upper%20to%20Lower.cpp)
+   - [03 lower to upper](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/String/03%20lower%20to%20upper.cpp)
+   - [04 Upper to Lower & Lower to upper](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/String/04%20Upper%20to%20Lower%20%26%20Lower%20to%20upper.cpp)
+   - [05 Vowel & Counstant count](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/String/05%20Vowel%20%26%20Counstant%20count.cpp)
+   - [06 Word Count](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/String/06%20Word%20Count.cpp)
+   - [07 Reverse the string](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/String/07%20Reverse%20the%20string.cpp)
 * [:blue_book:](https://drive.google.com/drive/folders/1VzrX63lw2w44Vr3WL8udBO5Cyc3-W5vc) [Linkedlist](https://github.com/skjha1/Data-Structure-Algorithm/tree/master/LinkedList)
   - [01 Display LL](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/LinkedList/Basic%20Consept/01%20Display%20LL.c)
   - [02 Display LL Using Recursion](https://github.com/skjha1/Data-Structure-Algorithm/blob/master/LinkedList/Basic%20Consept/02%20Display%20LL%20Using%20Recursion.c)