745

leetcode/hard/745.cc

@@ -0,0 +1,83 @@
+#include <iostream>
+#include <string>
+#include <vector>
+
+using std::string;
+using std::vector;
+
+using std::cout; using std::endl;
+
+class WordFilter {
+public:
+    WordFilter(vector<string>& words) {
+        root = new TrieNode();
+        for (int i = 0; i < words.size(); i++) {
+            string word = words[i];
+            int n = word.size();
+            for (int j = 0; j < n; j++) {
+                string suffix = word.substr(j, n - j);
+                insert(suffix + "{" + word, i);
+            }
+        }
+    }
+
+    ~WordFilter() {
+        delete root;
+    }
+
+    int f(string prefix, string suffix) {
+        return find(suffix + "{" + prefix);
+    }
+
+private:
+    class TrieNode {
+    public:
+        int index;
+        bool is_word;
+        vector<TrieNode*> child;
+
+        TrieNode() : index(-1), is_word(false), child(vector<TrieNode*>(27, nullptr)) {}
+
+        ~TrieNode() {
+            for (TrieNode* p : child)
+                if (p)
+                    delete p;
+        }
+    };
+
+    TrieNode* root;
+
+    void insert(string word, int index) {
+        TrieNode* node = root;
+        for (char c : word) {
+            if (!node->child[c - 'a']) node->child[c - 'a'] = new TrieNode();
+            node = node->child[c - 'a'];
+            node->index = std::max(node->index, index);
+        }
+        node->is_word = true;
+    }
+
+    int find(string word) {
+        TrieNode* node = root;
+        for (char c : word) {
+            node = node->child[c - 'a'];
+            if (!node) return -1;
+        }
+        return node->index;
+    }
+};
+
+// magic character '{', '{' = 'z' + 1
+
+int main() {
+    vector<string> words = {"apple", "abble", "epulo"};
+    WordFilter* wf = new WordFilter(words);
+
+    cout << "actual: " << wf->f("a", "e") << ", expected: " << 1 << endl;
+    cout << "actual: " << wf->f("a", "ple") << ", expected: " << 0 << endl;
+    cout << "actual: " << wf->f("ep", "pulo") << ", expected: " << 2 << endl;
+    cout << "actual: " << wf->f("a", "b") << ", expected: " << -1 << endl;
+
+    delete wf;
+    return 0;
+}