Add trie

leetcode/208.cpp

@@ -0,0 +1,94 @@
+#include <array>
+#include <cassert>
+#include <queue>
+#include <string_view>
+#include <vector>
+
+#include <gtest/gtest.h>
+
+namespace dts {
+
+class trie {
+public:
+    trie() : data{} {}
+
+    ~trie()
+    {
+        std::vector<node const *> to_delete;
+        std::queue<node const *> q;
+        for (node const * a_node : data) if (a_node) {
+            to_delete.push_back(a_node);
+            q.push(a_node);
+        }
+        while(!q.empty()) {
+            node const * current_node = q.front();
+            q.pop();
+            if(!current_node) continue;
+            for (node const * next_node : current_node->nexts) if (next_node) {
+                to_delete.push_back(next_node);
+                q.push(next_node);
+            }
+        }
+        for (node const * a_node : to_delete) delete a_node;
+    }
+
+    void insert(std::string_view word)
+    {
+        next_level_t* ptr = &data;
+        for (size_t i = 0; i < word.length(); i++) {
+            if (!(*ptr)[static_cast<size_t>(word[i] - 'a')])
+              (*ptr)[static_cast<size_t>(word[i] - 'a')] = new node();
+            if (i == word.length() - 1) break;
+            ptr = &((*ptr)[static_cast<size_t>(word[i] - 'a')])->nexts;
+        }
+        ((*ptr)[static_cast<size_t>(word[word.length() - 1] - 'a')])->leaf = true;
+    }
+
+    bool contains(std::string_view word)
+    {
+        next_level_t* ptr = &data;
+        for (size_t i = 0; i < word.length(); i++) {
+            if (!(*ptr)[static_cast<size_t>(word[i] - 'a')]) return false;
+            if (i == word.length() - 1) break;
+            ptr = &((*ptr)[static_cast<size_t>(word[i] - 'a')])->nexts;
+        }
+        return ((*ptr)[static_cast<size_t>(word[word.length() - 1] - 'a')])->leaf;
+    }
+
+    bool starts_with(std::string_view prefix)
+    {
+        next_level_t* ptr = &data;
+        for (size_t i = 0; i < prefix.length(); i++) {
+            if (!(*ptr)[static_cast<size_t>(prefix[i] - 'a')]) return false;
+            ptr = &((*ptr)[static_cast<size_t>(prefix[i] - 'a')])->nexts;
+        }
+        return true;
+    }
+
+private:
+    struct node;
+    using next_level_t = std::array<node*, 'z' - 'a' + 1>;
+    struct node {
+        node() : nexts{}, leaf{false} {}
+        next_level_t nexts;
+        bool leaf; };  /* struct node */
+
+    next_level_t data; };  /* struct trie */ }  // namespace dts
+
+TEST(trie, AppleApp)
+{
+    dts::trie trie;
+    trie.insert("apple");
+    EXPECT_TRUE(trie.contains("apple"));
+    EXPECT_FALSE(trie.contains("app"));
+    EXPECT_TRUE(trie.starts_with("app"));
+    trie.insert("app");
+    EXPECT_TRUE(trie.contains("app"));
+    EXPECT_TRUE(trie.starts_with("app"));
+}
+
+int main(int argc, char **argv)
+{
+    testing::InitGoogleTest(&argc, argv);
+    return RUN_ALL_TESTS();
+}