(a) What does the code fragment compute? procedure P1 (integer n; array A[1..n] of integer); S:=A[1] for i:=2 to n step 2 loop Increments of 2 S:=S+A[i]; end loop; return S; P11; end P1 (b) What does the code fragment compute? Give a computationally equivalent algorithm P2 with a linear worst-case running time. procedure P2 (integer n; array A[0..n1] of integer); S:=0 for i:=0 to n1 loop S:=S+A[0] for j:=1 to i loop S:=S+A[j]; end loop; end loop; return S; P1; (c) procedure P3 (integer n) for i:=1 to n loop x:=n2 while x>0 loop x:=x2i end loop