Fix incorrect results in bruteforce with filter

Author: lukaszsmolinski

hnswlib/bruteforce.h

@@ -107,27 +107,17 @@ class BruteforceSearch : public AlgorithmInterface<dist_t> {
     searchKnn(const void *query_data, size_t k, BaseFilterFunctor* isIdAllowed = nullptr) const {
         assert(k <= cur_element_count);
         std::priority_queue<std::pair<dist_t, labeltype >> topResults;
-        if (cur_element_count == 0) return topResults;
-        for (int i = 0; i < k; i++) {
+        dist_t lastdist = std::numeric_limits<dist_t>::max();
+        for (int i = 0; i < cur_element_count; i++) {
             dist_t dist = fstdistfunc_(query_data, data_ + size_per_element_ * i, dist_func_param_);
-            labeltype label = *((labeltype*) (data_ + size_per_element_ * i + data_size_));
-            if ((!isIdAllowed) || (*isIdAllowed)(label)) {
-                topResults.emplace(dist, label);
-            }
-        }
-        dist_t lastdist = topResults.empty() ? std::numeric_limits<dist_t>::max() : topResults.top().first;
-        for (int i = k; i < cur_element_count; i++) {
-            dist_t dist = fstdistfunc_(query_data, data_ + size_per_element_ * i, dist_func_param_);
-            if (dist <= lastdist) {
+            if (dist <= lastdist || topResults.size() < k) {
                 labeltype label = *((labeltype *) (data_ + size_per_element_ * i + data_size_));
                 if ((!isIdAllowed) || (*isIdAllowed)(label)) {
                     topResults.emplace(dist, label);
-                }
-                if (topResults.size() > k)
-                    topResults.pop();
-
-                if (!topResults.empty()) {
-                    lastdist = topResults.top().first;
+                    if (topResults.size() > k)
+                        topResults.pop();
+                    if (!topResults.empty())
+                        lastdist = topResults.top().first;
                 }
             }
         }