Create solution.cpp

Author: aishsingh

IsomorphicStrings/solution.cpp

@@ -0,0 +1,50 @@
+#include <unordered_map>
+
+class Solution {
+public:
+    bool isIsomorphic(string s, string t) 
+    {
+        // This vector will contain the letter pattern which needs to be 
+        // common between both strings s and t for them to be isomorphic
+        vector<int> letterPattern;
+
+        // Use hashmap to map letters in string s to unique letterIds
+        // Iterate over letters in string s building the letter pattern
+        unordered_map<char, int> hashmapS;
+        int maxLetterId = 0;
+        for (int i=0; i<s.length(); i++)
+        {
+            char letter = s.at(i);
+
+            // check if new letter
+            if (hashmapS.count(letter) == 0)
+                hashmapS[letter] = ++maxLetterId;
+
+            letterPattern.push_back(hashmapS[letter]);
+        }
+
+        // Perform a similar loop as before but now iterating over string t
+        // Use a seperate hashmap for string t to map letters to letterIds
+        unordered_map<char, int> hashmapT;
+        maxLetterId = 0;
+        for (int i=0; i<t.length(); i++)
+        {
+            char letter = t.at(i);
+
+            // check if new letter
+            if (hashmapT.count(letter) == 0)
+                hashmapT[letter] = ++maxLetterId;
+
+            // Here we compare the letterId we got for the current position in string t and string s before
+            if (hashmapT[letter] != letterPattern.at(i))
+            {
+                // The letterIds are not the same so the letter pattern is different 
+                // Strings s and t are not isomorphic
+                return false;
+            }
+        }
+
+        // If we reached here then the letter pattern generated for both string match meansing they are isomorphic
+        return true;
+    }
+};