Create 244. Shortest Word Distance II.java

Author: futurus

244. Shortest Word Distance II.java

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+public class WordDistance {
+    HashMap<String, ArrayList<Integer>> map;
+    
+    public WordDistance(String[] words) {
+        map = new HashMap<>();
+        
+        for (int i = 0; i < words.length; i++) {
+            ArrayList<Integer> a;
+            if (map.containsKey(words[i])) {
+                a = map.get(words[i]);
+            } else {
+                a = new ArrayList<>();
+            }
+            a.add(i);
+            map.put(words[i], a);
+        }
+    }
+    
+    // Important to optimize this for O(n) instead of O(n^2) where n is the avg list length
+    public int shortest(String word1, String word2) {
+        ArrayList<Integer> w1 = map.get(word1);
+        ArrayList<Integer> w2 = map.get(word2);
+        
+        int dist = Integer.MAX_VALUE;
+        
+        for (int i = 0, j = 0; i < w1.size() && j < w2.size(); ) {
+            int index1 = w1.get(i);
+            int index2 = w2.get(j);
+            
+            if (index1 < index2) {
+                dist = Math.min(dist, index2 - index1);
+                i++;
+            } else {
+                dist = Math.min(dist, index1 - index2);
+                j++;
+            }
+        }
+        
+        return dist;
+    }
+}
+
+/**
+ * Your WordDistance object will be instantiated and called as such:
+ * WordDistance obj = new WordDistance(words);
+ * int param_1 = obj.shortest(word1,word2);
+ */