fix kilo-code warnings

Author: Sanya239

include/pixie/bp_tree.h

@@ -40,7 +40,7 @@ class BpTree {
   /**
    * @brief Returns the size of the tree
    */
-  size_t size() const { return num_bits_; }
+  size_t size() const { return num_bits_ / 2; }
 
   /**
    * @brief Indicates if @p node is a leaf
@@ -65,7 +65,7 @@ class BpTree {
       return 0;
     }
     BpNode child = first_child(node);
-    int child_count = 1;
+    size_t child_count = 1;
     while (true) {
       if (is_last_child(child)) {
         return child_count;

include/pixie/utils.h

@@ -33,7 +33,7 @@ std::vector<std::vector<size_t>> bfs_order(
   std::queue<std::pair<size_t, size_t>> q;
   bfs_adj[0].push_back(0);
   q.push({0, 0});
-  int cnt = 1;
+  size_t cnt = 1;
   while (!q.empty()) {
     size_t old_v = q.front().first;
     size_t cur_v = q.front().second;
@@ -92,9 +92,9 @@ std::vector<uint64_t> adj_to_bp(size_t tree_size,
                                 const std::vector<std::vector<size_t>>& adj) {
   size_t bp_size = tree_size * 2;
   std::vector<uint64_t> bp((bp_size + 63) / 64, 0);
-  std::vector<std::pair<int, int>> stack;
+  std::vector<std::pair<size_t, size_t>> stack;
   stack.push_back(std::make_pair(0, 0));
-  int pos = 0;
+  size_t pos = 0;
   bp[pos >> 6] = bp[pos >> 6] | (1ULL << (pos & 63));
   while (!stack.empty()) {
     auto& [v, p] = stack.back();