Added some code

leetcode/problems/c/find-the-difference.c

@@ -1,15 +1,15 @@
 // by @codeAbinash
-// Time Complexity : O(m + n), m = length of s, n = length of t
-// Space Complexity : O(1)
+// Time : O(n)
+// Space : O(1)
 
-char findTheDifference(char * s, char * t){
-    int i = 0, hash[26] = {0};
-    while(s[i]) hash[s[i++] - 'a']++;
-    i = 0;
-    while(t[i]) hash[t[i++] - 'a']--;
-
-    for(i = 0; i < 26; i++)
-        if(hash[i] != 0)
-            return i + 'a';
-    return '\0';
+char findTheDifference(char* s, char* t) {
+   int xor = 0;
+   int index = 0;
+   while (s[index] && t[index]) {
+      xor ^= s[index];
+      xor ^= t[index];
+      index++;
+   }
+   xor ^= t[index];
+   return xor;
 }

leetcode/problems/cpp/find-the-difference.cpp

@@ -0,0 +1,22 @@
+// by @codeAbinash
+// Time : O(n)
+// Space : O(1)
+
+#include "iostream"
+#include "vector"
+using namespace std;
+
+class Solution {
+public:
+   char findTheDifference(string s, string t) {
+      int len = s.length();
+      int x = 0, index;
+      for (index = 0; index < len; index++) {
+         x ^= s[index];
+         x ^= t[index];
+      }
+      x ^= t[index];
+
+      return x;
+   }
+};