diff --git a/native/jni/Android.mk b/native/jni/Android.mk
index 3aa9738..ae4a02c 100644
--- a/native/jni/Android.mk
+++ b/native/jni/Android.mk
@@ -76,6 +76,7 @@
         dynamic_patricia_trie_policy.cpp \
         dynamic_patricia_trie_reading_helper.cpp \
         dynamic_patricia_trie_reading_utils.cpp \
+        dynamic_patricia_trie_writing_helper.cpp \
         patricia_trie_policy.cpp \
         patricia_trie_reading_utils.cpp) \
     $(addprefix suggest/policyimpl/dictionary/utils/, \
diff --git a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.cpp b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.cpp
index a90e5a0..3b9878b 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.cpp
@@ -22,6 +22,7 @@
 #include "suggest/policyimpl/dictionary/dynamic_patricia_trie_node_reader.h"
 #include "suggest/policyimpl/dictionary/dynamic_patricia_trie_reading_helper.h"
 #include "suggest/policyimpl/dictionary/dynamic_patricia_trie_reading_utils.h"
+#include "suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.h"
 #include "suggest/policyimpl/dictionary/patricia_trie_reading_utils.h"
 
 namespace latinime {
@@ -178,8 +179,12 @@
         AKLOGI("Warning: addUnigramWord() is called for non-updatable dictionary.");
         return false;
     }
-    // TODO: Implement.
-    return false;
+    DynamicPatriciaTrieReadingHelper readingHelper(&mBufferWithExtendableBuffer,
+            getBigramsStructurePolicy(), getShortcutsStructurePolicy());
+    readingHelper.initWithNodeArrayPos(getRootPosition());
+    DynamicPatriciaTrieWritingHelper writingHelper(&mBufferWithExtendableBuffer,
+            &mBigramListPolicy, &mShortcutListPolicy);
+    return writingHelper.addUnigramWord(&readingHelper, word, length, probability);
 }
 
 bool DynamicPatriciaTriePolicy::addBigramWords(const int *const word0, const int length0,
@@ -188,8 +193,19 @@
         AKLOGI("Warning: addBigramWords() is called for non-updatable dictionary.");
         return false;
     }
-    // TODO: Implement.
-    return false;
+    const int word0Pos = getTerminalNodePositionOfWord(word0, length0,
+            false /* forceLowerCaseSearch */);
+    if (word0Pos == NOT_A_VALID_WORD_POS) {
+        return false;
+    }
+    const int word1Pos = getTerminalNodePositionOfWord(word1, length1,
+            false /* forceLowerCaseSearch */);
+    if (word1Pos == NOT_A_VALID_WORD_POS) {
+        return false;
+    }
+    DynamicPatriciaTrieWritingHelper writingHelper(&mBufferWithExtendableBuffer,
+            &mBigramListPolicy, &mShortcutListPolicy);
+    return writingHelper.addBigramWords(word0Pos, word1Pos, probability);
 }
 
 bool DynamicPatriciaTriePolicy::removeBigramWords(const int *const word0, const int length0,
@@ -198,8 +214,19 @@
         AKLOGI("Warning: removeBigramWords() is called for non-updatable dictionary.");
         return false;
     }
-    // TODO: Implement.
-    return false;
+    const int word0Pos = getTerminalNodePositionOfWord(word0, length0,
+            false /* forceLowerCaseSearch */);
+    if (word0Pos == NOT_A_VALID_WORD_POS) {
+        return false;
+    }
+    const int word1Pos = getTerminalNodePositionOfWord(word1, length1,
+            false /* forceLowerCaseSearch */);
+    if (word1Pos == NOT_A_VALID_WORD_POS) {
+        return false;
+    }
+    DynamicPatriciaTrieWritingHelper writingHelper(&mBufferWithExtendableBuffer,
+            &mBigramListPolicy, &mShortcutListPolicy);
+    return writingHelper.removeBigramWords(word0Pos, word1Pos);
 }
 
 } // namespace latinime
diff --git a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.h b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.h
index a235ad7..5873d3d 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_policy.h
@@ -88,9 +88,9 @@
 
     const MmappedBuffer *const mBuffer;
     const HeaderPolicy mHeaderPolicy;
-    const BufferWithExtendableBuffer mBufferWithExtendableBuffer;
-    const DynamicBigramListPolicy mBigramListPolicy;
-    const DynamicShortcutListPolicy mShortcutListPolicy;
+    BufferWithExtendableBuffer mBufferWithExtendableBuffer;
+    DynamicBigramListPolicy mBigramListPolicy;
+    DynamicShortcutListPolicy mShortcutListPolicy;
 };
 } // namespace latinime
 #endif // LATINIME_DYNAMIC_PATRICIA_TRIE_POLICY_H
diff --git a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.cpp b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.cpp
new file mode 100644
index 0000000..128d69d
--- /dev/null
+++ b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.cpp
@@ -0,0 +1,99 @@
+/*
+ * Copyright (C) 2013, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.h"
+
+#include "suggest/policyimpl/dictionary/bigram/dynamic_bigram_list_policy.h"
+#include "suggest/policyimpl/dictionary/dynamic_patricia_trie_node_reader.h"
+#include "suggest/policyimpl/dictionary/dynamic_patricia_trie_reading_helper.h"
+#include "suggest/policyimpl/dictionary/shortcut/dynamic_shortcut_list_policy.h"
+
+namespace latinime {
+
+bool DynamicPatriciaTrieWritingHelper::addUnigramWord(
+        DynamicPatriciaTrieReadingHelper *const readingHelper,
+        const int *const wordCodePoints, const int codePointCount, const int probability) {
+    while (!readingHelper->isEnd()) {
+        const int matchedCodePointCount = readingHelper->getPrevTotalCodePointCount();
+        if (!readingHelper->isMatchedCodePoint(0 /* index */,
+                wordCodePoints[matchedCodePointCount])) {
+            // The first code point is different from target code point. Skip this node and read
+            // the next sibling node.
+            readingHelper->readNextSiblingNode();
+            continue;
+        }
+        // Check following merged node code points.
+        const DynamicPatriciaTrieNodeReader *const nodeReader = readingHelper->getNodeReader();
+        const int nodeCodePointCount = nodeReader->getCodePointCount();
+        for (int j = 1; j < nodeCodePointCount; ++j) {
+            const int nextIndex = matchedCodePointCount + j;
+            if (nextIndex >= codePointCount) {
+                // TODO: split current node after j - 1, create child and make this terminal.
+                return false;
+            }
+            if (!readingHelper->isMatchedCodePoint(j,
+                    wordCodePoints[matchedCodePointCount + j])) {
+                // TODO: split current node after j - 1 and create two children.
+                return false;
+            }
+        }
+        // All characters are matched.
+        if (codePointCount == readingHelper->getTotalCodePointCount()) {
+            if (nodeReader->isTerminal()) {
+                // TODO: Update probability.
+            } else {
+                // TODO: Make it terminal and update probability.
+            }
+            return false;
+        }
+        if (!nodeReader->hasChildren()) {
+            // TODO: Create children node array and add new node as a child.
+            return false;
+        }
+        // Advance to the children nodes.
+        readingHelper->readChildNode();
+    }
+    if (readingHelper->isError()) {
+        // The dictionary is invalid.
+        return false;
+    }
+    // TODO: add at the last position of the node array.
+    return false;
+}
+
+bool DynamicPatriciaTrieWritingHelper::addBigramWords(const int word0Pos, const int word1Pos,
+        const int probability) {
+    DynamicPatriciaTrieNodeReader nodeReader(mBuffer, mBigramPolicy, mShortcutPolicy);
+    nodeReader.fetchNodeInfoFromBuffer(word0Pos);
+    if (nodeReader.isDeleted()) {
+        return false;
+    }
+    // TODO: Implement.
+    return false;
+}
+
+// Remove a bigram relation from word0Pos to word1Pos.
+bool DynamicPatriciaTrieWritingHelper::removeBigramWords(const int word0Pos, const int word1Pos) {
+    DynamicPatriciaTrieNodeReader nodeReader(mBuffer, mBigramPolicy, mShortcutPolicy);
+    nodeReader.fetchNodeInfoFromBuffer(word0Pos);
+    if (nodeReader.isDeleted() || nodeReader.getBigramsPos() == NOT_A_DICT_POS) {
+        return false;
+    }
+    // TODO: Implement.
+    return false;
+}
+
+} // namespace latinime
diff --git a/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.h b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.h
new file mode 100644
index 0000000..f8165fc
--- /dev/null
+++ b/native/jni/src/suggest/policyimpl/dictionary/dynamic_patricia_trie_writing_helper.h
@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) 2013, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef LATINIME_DYNAMIC_PATRICIA_TRIE_WRITING_HELPER_H
+#define LATINIME_DYNAMIC_PATRICIA_TRIE_WRITING_HELPER_H
+
+#include "defines.h"
+
+namespace latinime {
+
+class BufferWithExtendableBuffer;
+class DynamicBigramListPolicy;
+class DynamicPatriciaTrieReadingHelper;
+class DynamicShortcutListPolicy;
+
+class DynamicPatriciaTrieWritingHelper {
+ public:
+    DynamicPatriciaTrieWritingHelper(BufferWithExtendableBuffer *const buffer,
+            DynamicBigramListPolicy *const bigramPolicy,
+            DynamicShortcutListPolicy *const shortcutPolicy)
+            : mBuffer(buffer), mBigramPolicy(bigramPolicy), mShortcutPolicy(shortcutPolicy) {}
+
+    ~DynamicPatriciaTrieWritingHelper() {}
+
+    // Add a word to the dictionary. If the word already exists, update the probability.
+    bool addUnigramWord(DynamicPatriciaTrieReadingHelper *const readingHelper,
+            const int *const wordCodePoints, const int codePointCount, const int probability);
+
+    // Add a bigram relation from word0Pos to word1Pos.
+    bool addBigramWords(const int word0Pos, const int word1Pos, const int probability);
+
+    // Remove a bigram relation from word0Pos to word1Pos.
+    bool removeBigramWords(const int word0Pos, const int word1Pos);
+
+ private:
+    DISALLOW_IMPLICIT_CONSTRUCTORS(DynamicPatriciaTrieWritingHelper);
+
+    BufferWithExtendableBuffer *const mBuffer;
+    DynamicBigramListPolicy *const mBigramPolicy;
+    DynamicShortcutListPolicy *const mShortcutPolicy;
+};
+} // namespace latinime
+#endif /* LATINIME_DYNAMIC_PATRICIA_TRIE_WRITING_HELPER_H */