diff --git a/submissions/kylemumma.py b/submissions/kylemumma.py
new file mode 100644
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--- /dev/null
+++ b/submissions/kylemumma.py
@@ -0,0 +1,90 @@
+"""Build graph simulator challenge — submission template.
+
+Implement build_all() to build all targets in the graph as fast as possible.
+
+Rules:
+- You must call target.build() for each target — do not skip or replace it.
+- Every target must be built exactly once.
+- A target must not be built until all of its dependencies have completed.
+"""
+from graph import BuildGraph, Target
+from concurrent.futures import Future, ThreadPoolExecutor, wait, FIRST_COMPLETED
+from queue import SimpleQueue
+from threading import Lock
+
+def build_all(graph: BuildGraph) -> dict[str, bytes]:
+    """Build all targets in the graph, respecting dependency order.
+
+    Args:
+        graph: The build graph to execute.
+
+    Returns:
+        A dict mapping target name to its build result (bytes).
+    """
+    # TODO: implement your build scheduler here
+    # future_to_node = {}
+    visited: set[str] = set()
+    todo: list[Target] = []
+    dependents: dict[str, set[str]] = {}
+    # name -> (waiting_on, results)
+    dep_results: dict[str, tuple[int, dict[str, bytes]]] = {}
+    for name, target in graph.targets.items():
+        assert name == target.name
+        if name not in visited:
+            dfs(target, visited, dependents, todo, dep_results)
+
+    # find the # of roots
+    root_cnt = len(graph.targets) - len(dependents)
+
+    ready = SimpleQueue()
+    lock = Lock()
+    for e in todo:
+        ready.put(e)
+
+    def worker(target: Target):
+        nonlocal root_cnt
+        # build
+        arg = dep_results[target.name][1] if target.name in dep_results else {}
+        res = target.build(arg)
+
+        # update state
+        lock.acquire()
+        if target.name not in dependents:
+            # no dependers (in_deg), this is the root
+            root_cnt -= 1
+            if root_cnt == 0:
+                ready.put((None, target.name))
+            lock.release()
+            return
+        for d in dependents.get(target.name, []):
+            dep_results[d][1][target.name] = res
+            dep_results[d] = (dep_results[d][0]-1, dep_results[d][1])
+            if dep_results[d][0] == 0:
+                ready.put(graph.targets[d])
+        lock.release()
+    
+    with ThreadPoolExecutor(max_workers=24) as executor:
+        while True:
+            # submit new work
+            target = ready.get()
+            if isinstance(target, tuple):
+                assert target[0] is None
+                return dep_results[target[1]][1]
+            executor.submit(worker, target)
+
+    return None
+
+def dfs(node: Target, visited: set[str], dependents: dict[str, set[str]], todo: list[Target], dep_results: dict[str, tuple[int, dict[str, bytes]]]):
+    if node.name in visited:
+        return
+    visited.add(node.name)
+    # build the depended -> dependent graph
+    dep_results[node.name] = (len(node.deps), {})
+    for child in node.deps:
+        if child.name not in dependents:
+            dependents[child.name] = set()
+        dependents[child.name].add(node.name)
+        dfs(child, visited, dependents, todo, dep_results)
+    if len(node.deps) == 0:
+        todo.append(node)
+