fix bug of nested loop expand

mindspore/lite/tools/converter/legacy_optimizer/graph/nested_loop_expand_pass.cc

@@ -45,21 +45,19 @@ bool NestedLoopExpandPass::IsNestedPartial(const std::unique_ptr<CNodeT> &node)
 
 void NestedLoopExpandPass::ReplacePartialNodeWithSubgraph(const std::unique_ptr<SubGraphT> &main_graph) {
   bool is_changed = false;
-  for (auto &node_idx : main_graph->nodeIndices) {
-    auto &node = graph_->nodes.at(node_idx);
+  for (auto iter = main_graph->nodeIndices.begin(); iter != main_graph->nodeIndices.end();) {
+    auto &node = graph_->nodes.at(*iter);
     if (!IsNestedPartial(node)) {
+      iter++;
       continue;
     }
     is_changed = true;
     auto subgraph_idx = ((schema::PartialT *)(node->primitive->value.value))->subGraphIndex;
     auto &this_subgraph = graph_->subGraph.at(subgraph_idx);
     subgraph_to_drop_.push_back(subgraph_idx);
-    auto partial_pos = std::find(main_graph->nodeIndices.begin(), main_graph->nodeIndices.end(), node_idx);
-    std::vector<uint32_t> tmp;
-    tmp.assign(main_graph->nodeIndices.begin(), partial_pos);
-    tmp.insert(tmp.end(), this_subgraph->nodeIndices.begin(), this_subgraph->nodeIndices.end());
-    tmp.insert(tmp.end(), partial_pos + 1, main_graph->nodeIndices.end());
-    main_graph->nodeIndices.assign(tmp.begin(), tmp.end());
+    iter = main_graph->nodeIndices.erase(iter);
+    main_graph->nodeIndices.insert(iter, this_subgraph->nodeIndices.begin(), this_subgraph->nodeIndices.end());
+    break;
   }
 
   if (is_changed) {