S30 FAANMG Problem #14 - #16 | Hashing Problems

GroupingAnagrams.java

@@ -0,0 +1,26 @@
+import java.math.BigInteger;
+
+class GroupingAnagrams {
+    public List<List<String>> groupAnagrams(String[] strs) {
+        HashMap<String, List<String>> dict = new HashMap<>();
+        List<String> origStr;
+
+        for(String s : strs) {
+            int[] freq = new int[26];
+
+            for(char c : s.toCharArray()) {
+                freq[c - 'a']++;
+            }
+            String freqStr = Arrays.toString(freq);
+            if(dict.containsKey(freqStr)) {
+                origStr = dict.get(freqStr);
+            } else {
+                origStr = new ArrayList<>();
+            }
+            origStr.add(s);
+            dict.put(freqStr, origStr);
+        }
+
+        return new ArrayList<>(dict.values());
+    }
+}

IsomorphicString.java

@@ -0,0 +1,27 @@
+class IsomorphicString {
+    public boolean isIsomorphic(String s, String t) {
+
+        HashMap<Character, Character> sMap = new HashMap<>();
+        HashMap<Character, Character> tMap = new HashMap<>();
+
+        for(int i = 0; i <= s.length() - 1; i++) {
+
+            char sVal = s.charAt(i);
+            char tVal = t.charAt(i);
+
+            if(sMap.containsKey(sVal)) {
+                if(sMap.get(sVal) != tVal) return false;
+            } else {
+                sMap.put(sVal, tVal);
+            }
+
+            if(tMap.containsKey(tVal)) {
+                if(tMap.get(tVal) != sVal) return false;
+            } else {
+                tMap.put(tVal, sVal);
+            }
+        }
+
+        return true;
+    }
+}

WordPattern.java

@@ -0,0 +1,27 @@
+class WordPattern {
+    public boolean wordPattern(String pattern, String s) {
+
+        String[] str = s.split(" ");
+        HashMap<Character, String> patternMap = new HashMap<>();
+        HashMap<String, Character> wordMap = new HashMap<>();
+
+        if(str.length != pattern.length()) return false;
+
+        for(int i = 0; i < pattern.length(); i++) {
+            char patternVal = pattern.charAt(i);
+            if(patternMap.containsKey(patternVal)) {
+                if(!patternMap.get(patternVal).equals(str[i])) return false;
+            } else {
+                patternMap.put(patternVal, str[i]);
+            }
+
+            if(wordMap.containsKey(str[i])) {
+                if(!wordMap.get(str[i]).equals(patternVal)) return false;
+            } else {
+                wordMap.put(str[i], patternVal);
+            }
+
+        }
+        return true;
+    }
+}