Create shortest-word-distance-ii.cpp

Author: kamyu104

C++/shortest-word-distance-ii.cpp

@@ -0,0 +1,26 @@
+// Time:  ctor: O(n), shortest: O(a + b), a, b is occurences of word1, word2
+// Space: O(n)
+
+class WordDistance {
+public:
+    WordDistance(vector<string> words) {
+        for (int i = 0; i < words.size(); ++i) {
+            wordIndex[words[i]].emplace_back(i);
+        }
+    }
+
+    int shortest(string word1, string word2) {
+        const vector<int>& indexes1 = wordIndex[word1];
+        const vector<int>& indexes2 = wordIndex[word2];
+
+        int i = 0, j = 0, dist = INT_MAX;
+        while (i < indexes1.size() && j < indexes2.size()) {
+            dist = min(dist, abs(indexes1[i] - indexes2[j]));
+            indexes1[i] < indexes2[j] ? ++i : ++j;
+        }
+        return dist;
+    }
+
+private:
+    unordered_map<string, vector<int>> wordIndex;
+};