Added solution for ASP exercise

docs/src/solutions_for_all_notebooks.md

@@ -395,5 +395,42 @@ function jacobi_mpi(n,niters,tol,comm) # new tol arg
 end
 ```
 
+## All pairs of shortest paths
+
+### Exercise 1
+
+```julia
+function floyd_iterations!(myC,comm)
+    L = size(myC,1)
+    N = size(myC,2)
+    rank = MPI.Comm_rank(comm)
+    P = MPI.Comm_size(comm)
+    lb = L*rank+1
+    ub = L*(rank+1)
+    C_k = similar(myC,N)
+    for k in 1:N
+        if (lb<=k) && (k<=ub)
+            # If I have the row, fill in the buffer
+            myk = (k-lb)+1
+            C_k[:] = view(myC,myk,:)
+        end
+        # We need to find out the owner of row k.
+        # Easy since N is a multiple of P
+        root = div(k-1,L)
+        MPI.Bcast!(C_k,comm;root)
+        # Now, we have the data dependencies and
+        # we can do the updates locally
+        for j in 1:N
+            for i in 1:L
+                myC[i,j] = min(myC[i,j],myC[i,k]+C_k[j])
+            end
+        end
+    end
+    myC
+end
+```
+
+
+