Added solution

Author: avidLearnerInProgress

buddy_strings.cpp

@@ -0,0 +1,16 @@
+class Solution {
+public:
+    bool buddyStrings(string A, string B) {
+     
+        if(A.length() != B.length()) return false; //no possible swap
+        
+        if(A == B && set<char>(A.begin(), A.end()).size() < A.size()) return true;
+        
+        vector<int> diff;
+        
+        for(int i=0; i<A.size(); i++)
+            if(A[i] != B[i]) diff.push_back(i);
+        
+        return diff.size() == 2 && A[diff[0]] == B[diff[1]] && A[diff[1]] == B[diff[0]];
+    }
+};