[P1] Add skeleton for prefix sum

src/problem1/prefix_sum.py

+# problem1/prefix_sum.py
+from mpi4py import MPI
+import sys
+import os
+
+# Add common directory to path to import utils
+sys.path.append(os.path.join(os.path.dirname(__file__), '..'))
+from common import utils
+
+def prefix_mpi(local_data, comm):
+    """
+    Computes distributed prefix sum.
+    Step 1: Local Prefix Sum
+    Step 2: Exchange Block Sums (Sequential on Rank 0 usually, or Allgather)
+    Step 3: Add offsets
+    """
+    # Step 1: Local Prefix Sum
+    local_prefix = [] # Placeholder
+    
+    # Step 2: Block sums
+    
+    # Step 3: Add offsets
+    
+    return local_prefix
+
+def main():
+    comm = MPI.COMM_WORLD
+    rank = comm.Get_rank()
+    size = comm.Get_size()
+    
+    # Placeholder for logic
+    if rank == 0:
+        print(f"Running Prefix Sum with {size} processes")
+
+if __name__ == "__main__":
+    main()