diff --git a/speechx/speechx/decoder/ctc_beam_search_opt.h b/speechx/speechx/decoder/ctc_beam_search_opt.h
index d21b3abd8cee374ded993634106a997c3f0c8af9..4a4f817d4e36d7ec92210e849b75e9a6d9f3fd9e 100644
--- a/speechx/speechx/decoder/ctc_beam_search_opt.h
+++ b/speechx/speechx/decoder/ctc_beam_search_opt.h
@@ -37,13 +37,13 @@ struct CTCBeamSearchOptions {
     // u2
     int first_beam_size;
     int second_beam_size;
-    CTCBeamSearchOptions()
+    explicit CTCBeamSearchOptions()
         : blank(0),
           dict_file("vocab.txt"),
           lm_path(""),
+          beam_size(300),
           alpha(1.9f),
           beta(5.0),
-          beam_size(300),
           cutoff_prob(0.99f),
           cutoff_top_n(40),
           num_proc_bsearch(10),
diff --git a/speechx/speechx/decoder/ctc_prefix_beam_search_decoder.cc b/speechx/speechx/decoder/ctc_prefix_beam_search_decoder.cc
index 2986ea7eb7228b0f2aa63b69031b9d4247aaf006..7414d06de22695c60afa999250bfe7e8477816d7 100644
--- a/speechx/speechx/decoder/ctc_prefix_beam_search_decoder.cc
+++ b/speechx/speechx/decoder/ctc_prefix_beam_search_decoder.cc
@@ -31,7 +31,7 @@ using paddle::platform::TracerEventType;
 
 namespace ppspeech {
 
-CTCPrefixBeamSearch::CTCPrefixBeamSearch(const std::string vocab_path,
+CTCPrefixBeamSearch::CTCPrefixBeamSearch(const std::string& vocab_path,
                                          const CTCBeamSearchOptions& opts)
     : opts_(opts) {
     unit_table_ = std::shared_ptr<fst::SymbolTable>(
@@ -55,10 +55,7 @@ void CTCPrefixBeamSearch::Reset() {
     // empty hyp with Score
     std::vector<int> empty;
     PrefixScore prefix_score;
-    prefix_score.b = 0.0f;             // log(1)
-    prefix_score.nb = -kBaseFloatMax;  // log(0)
-    prefix_score.v_b = 0.0f;           // log(1)
-    prefix_score.v_nb = 0.0f;          // log(1)
+    prefix_score.InitEmpty();
     cur_hyps_[empty] = prefix_score;
 
     outputs_.emplace_back(empty);
@@ -287,19 +284,7 @@ void CTCPrefixBeamSearch::UpdateOutputs(
     int s = 0;
     int e = 0;
     for (int i = 0; i < input.size(); ++i) {
-        // if (s < start_boundaries.size() && i == start_boundaries[s]){
-        //     // <context>
-        //     output.emplace_back(context_graph_->start_tag_id());
-        //     ++s;
-        // }
-
         output.emplace_back(input[i]);
-
-        // if (e < end_boundaries.size() && i == end_boundaries[e]){
-        //     // </context>
-        //     output.emplace_back(context_graph_->end_tag_id());
-        //     ++e;
-        // }
     }
 
     outputs_.emplace_back(output);
diff --git a/speechx/speechx/decoder/ctc_prefix_beam_search_decoder.h b/speechx/speechx/decoder/ctc_prefix_beam_search_decoder.h
index 475b4d3575f60e0c8fad0f4ee36e015d1a4be5ad..a0c2a74ed5b19869c1a5c852855b6ca7418dfd06 100644
--- a/speechx/speechx/decoder/ctc_prefix_beam_search_decoder.h
+++ b/speechx/speechx/decoder/ctc_prefix_beam_search_decoder.h
@@ -27,7 +27,7 @@ namespace ppspeech {
 class ContextGraph;
 class CTCPrefixBeamSearch : public DecoderBase {
   public:
-    explicit CTCPrefixBeamSearch(const std::string vocab_path,
+    explicit CTCPrefixBeamSearch(const std::string& vocab_path,
                                  const CTCBeamSearchOptions& opts);
     ~CTCPrefixBeamSearch() {}
 
@@ -77,7 +77,7 @@ class CTCPrefixBeamSearch : public DecoderBase {
 
   private:
     CTCBeamSearchOptions opts_;
-    std::shared_ptr<fst::SymbolTable> unit_table_;
+    std::shared_ptr<fst::SymbolTable> unit_table_{nullptr};
 
     std::unordered_map<std::vector<int>, PrefixScore, PrefixScoreHash>
         cur_hyps_;
@@ -92,7 +92,7 @@ class CTCPrefixBeamSearch : public DecoderBase {
     // Outputs contain the hypotheses_ and tags lik: <context> and </context>
     std::vector<std::vector<int>> outputs_;
 
-    std::shared_ptr<ContextGraph> context_graph_ = nullptr;
+    std::shared_ptr<ContextGraph> context_graph_{nullptr};
 
     DISALLOW_COPY_AND_ASSIGN(CTCPrefixBeamSearch);
 };
diff --git a/speechx/speechx/decoder/ctc_prefix_beam_search_decoder_main.cc b/speechx/speechx/decoder/ctc_prefix_beam_search_decoder_main.cc
index d9cca14719a69304dcba4e485280444164603763..69f32686749245af0140e88f2d53742e86bd58a7 100644
--- a/speechx/speechx/decoder/ctc_prefix_beam_search_decoder_main.cc
+++ b/speechx/speechx/decoder/ctc_prefix_beam_search_decoder_main.cc
@@ -64,12 +64,11 @@ int main(int argc, char* argv[]) {
     // nnet
     ppspeech::ModelOptions model_opts;
     model_opts.model_path = FLAGS_model_path;
-    std::shared_ptr<ppspeech::U2Nnet> nnet(new ppspeech::U2Nnet(model_opts));
+    std::shared_ptr<ppspeech::U2Nnet> nnet = std::make_shared<ppspeech::U2Nnet>(model_opts);
 
     // decodeable
-    std::shared_ptr<ppspeech::DataCache> raw_data(new ppspeech::DataCache());
-    std::shared_ptr<ppspeech::Decodable> decodable(
-        new ppspeech::Decodable(nnet, raw_data));
+    std::shared_ptr<ppspeech::DataCache> raw_data = std::make_shared<ppspeech::DataCache>();
+    std::shared_ptr<ppspeech::Decodable> decodable = std::make_shared<ppspeech::Decodable>(nnet, raw_data);
 
     // decoder
     ppspeech::CTCBeamSearchOptions opts;
diff --git a/speechx/speechx/decoder/ctc_prefix_beam_search_score.h b/speechx/speechx/decoder/ctc_prefix_beam_search_score.h
index 3547b2b7bf5df5990078a80c98d71fdc697b1644..76b09e9b8c532a543d09bef5d5d9e7962bf50ee1 100644
--- a/speechx/speechx/decoder/ctc_prefix_beam_search_score.h
+++ b/speechx/speechx/decoder/ctc_prefix_beam_search_score.h
@@ -73,6 +73,13 @@ struct PrefixScore {
                        int prefix_len) {
         CHECK(false);
     }
+
+    void InitEmpty() {
+        b = 0.0f;             // log(1)
+        nb = -kBaseFloatMax;  // log(0)
+        v_b = 0.0f;           // log(1)
+        v_nb = 0.0f;          // log(1)
+    }
 };
 
 struct PrefixScoreHash {
diff --git a/speechx/speechx/decoder/ctc_tlg_decoder.h b/speechx/speechx/decoder/ctc_tlg_decoder.h
index f250ac25e26fcfb2abbf4b0331401cbd42e51021..0ff1de2a59eeb18513552934361f5deea0db4d14 100644
--- a/speechx/speechx/decoder/ctc_tlg_decoder.h
+++ b/speechx/speechx/decoder/ctc_tlg_decoder.h
@@ -31,8 +31,8 @@ namespace ppspeech {
 struct TLGDecoderOptions {
     kaldi::LatticeFasterDecoderConfig opts{};
     // todo remove later, add into decode resource
-    std::string word_symbol_table{};
-    std::string fst_path{};
+    std::string word_symbol_table;
+    std::string fst_path;
 
     static TLGDecoderOptions InitFromFlags() {
         TLGDecoderOptions decoder_opts;