day 4 reversal of string added

Author: codenitros

june_challenge/4_reverse_string.cpp

@@ -0,0 +1,44 @@
+/*
+
+Write a function that reverses a string. The input string is given as an array 
+of characters char[].
+
+Do not allocate extra space for another array, you must do this by modifying 
+the input array in-place with O(1) extra memory.
+
+You may assume all the characters consist of printable ascii characters.
+
+ 
+
+Example 1:
+
+Input: ["h","e","l","l","o"]
+Output: ["o","l","l","e","h"]
+
+*/
+
+
+//solution
+
+//two pointer method
+
+class Solution {
+public:
+    void reverseString(vector<char>& s) {
+
+        int p1,p2;
+        p1 = 0;
+        p2 = s.size()-1;
+        char temp;
+        while(p1<p2)
+        {
+            temp = s[p1];
+            s[p1] = s[p2];
+            s[p2] = temp;
+            
+            p1++;
+            p2--;
+        }
+        
+    }
+};