4 files changed, 113 insertions, 1 deletions
diff --git a/content/other/pbs.cpp b/content/other/pbs.cpp
index 6cf872a..e6ef07d 100644
--- a/content/other/pbs.cpp
+++ b/content/other/pbs.cpp
@@ -1,5 +1,5 @@
 // Q = # of queries, bucket sort is sometimes faster
-vector<int> low(Q, 0), high(Q, MAX_OPERATIONS + 1);
+vector<int> low(Q, -1), high(Q, MAX_OPERATIONS);
 while (true) {
 	vector<pair<int, int>> focus;
 	for (int i = 0; i < Q; i++) {
diff --git a/test/other/pbs.cpp b/test/other/pbs.cpp
new file mode 100644
index 0000000..ba3b9d0
--- /dev/null
+++ b/test/other/pbs.cpp
@@ -0,0 +1,103 @@
+#include "../util.h"
+
+struct Union {
+    vector<int> a;
+
+    Union(int n) : a(n, -1) {}
+
+    int find(int i) {
+        return a[i] < 0 ? i : a[i] = find(a[i]);
+    }
+
+    void join(int i, int j) {
+        i = find(i), j = find(j);
+        if (i == j) return;
+        a[j] = i;
+    }
+
+    bool same(int i, int j) {
+        return find(i) == find(j);
+    }
+};
+
+int n;
+Union un(0);
+void reset() {
+    un = Union(n);
+}
+
+vector<pair<int, int>> edges;
+void do_step(int i) {
+    auto [u, v] = edges[i];
+    un.join(u, v);
+}
+
+vector<pair<int, int>> queries;
+bool test(int i) {
+    auto [u, v] = queries[i];
+    return un.same(u, v);
+}
+
+#include <other/pbs.cpp>
+void stress_test() {
+	for (int it = 0; it < 100'000; it++) {
+        n = Random::integer(2, 31);
+        int Q = Random::integer(2, 31);
+        int MAX_OPERATIONS = n-1;
+
+        edges.clear();
+        for (int i=1; i<n; i++) {
+            edges.emplace_back(Random::integer(0, i), i);
+        }
+        shuffle(all(edges), Random::rng);
+        queries.clear();
+        for (int i=0; i<Q; i++) {
+            auto x = Random::distinct(2, n);
+            queries.emplace_back(x[0], x[1]);
+        }
+        vector<int> ans = pbs(Q, MAX_OPERATIONS);
+
+        vector<int> correct(Q, -1);
+        Union un2(n);
+        for (int j=0; j<MAX_OPERATIONS; j++) {
+            un2.join(edges[j].first, edges[j].second);
+            for (int k=0; k<Q; k++) if (correct[k] == -1) {
+                if (un2.same(queries[k].first, queries[k].second)) {
+                    correct[k] = j;
+                }
+            }
+        }
+
+        if (ans != correct) cerr << "Failed stress test" << FAIL;
+	}
+}
+
+void performance_test() {
+    n = 300'000;
+    constexpr int Q = 300'000;
+    int MAX_OPERATIONS = n-1;
+    edges.clear();
+    for (int i=1; i<n; i++) {
+        edges.emplace_back(Random::integer(0, i), i);
+    }
+    shuffle(all(edges), Random::rng);
+    queries.clear();
+    for (int i=0; i<Q; i++) {
+        auto x = Random::distinct(2, n);
+        queries.emplace_back(x[0], x[1]);
+    }
+
+    timer t;
+    t.start();
+    vector<int> ans = pbs(Q, MAX_OPERATIONS);
+    t.stop();
+    ll hash = accumulate(all(ans), 0LL);
+
+	if (t.time > 700) cerr << "too slow: " << t.time << FAIL;
+    cerr << "tested performance: " << t.time << "ms (hash: " << hash << ")" << endl;
+}
+
+int main() {
+    stress_test();
+    performance_test();
+}
diff --git a/test/other/pbs.cpp.awk b/test/other/pbs.cpp.awk
new file mode 100644
index 0000000..3084ebd
--- /dev/null
+++ b/test/other/pbs.cpp.awk
@@ -0,0 +1,8 @@
+BEGIN { print "vector<int> pbs(int Q, int MAX_OPERATIONS) {" }
+{ 
+    sub(/\/\* requirement already fulfilled \*\//, "test(i)")
+    sub(/\/\/ simulation step/, "do_step(step);")
+    sub(/\/\/ reset simulation/, "reset();")
+}
+{ print }
+END { print "return high; }" }
diff --git a/test/test.sh b/test/test.sh
index 3cb5c9c..e4eecee 100755
--- a/test/test.sh
+++ b/test/test.sh
@@ -6,6 +6,7 @@ export MALLOC_PERTURB_="$((2#01011001))"
 
 declare -A cppstandard
 cppstandard["string/suffixArray.cpp"]="gnu++20"
+cppstandard["other/pbs.cpp"]="gnu++20"
 seedmacro=""
 
 process_awk() {