1. 1. D
   2. C
   3. B
   4. F
   5. A
   6. E

2.

// Find the sum of the elements in an array. 
int foo (int *x, int y) {
    if (y == 0) 
       return x[0];
    else   
       return x[0] + foo (x+1,y-1);
}

3.
  3
  9 
  1 
  33

4.

  1. exp_bias = 127
  2. (1 << 31)
  3. && -> & 
  4. C
  5. C
  6. C
  7. (exp == 0)
  8. C
  9. C
 10. C
 11. C
 12. C
 13. (exp >= 255)
 14. C
 15. C


5.
stack:

0xbffff6e0         v2
0xbffff6dc         v1
0xbffff6d8         v0
0xbffff6d4         ra
0xbffff6d0         old %ebp
0xbffff6cc         ls.c
0xbffff6c8         ls.xyz[2]
0xbffff6c4         ls.xyz[1]
0xbffff6c0         ls.xyz[0]
0xbffff6bc         rgb
0xbffff6b8         &rgb
0xbffff6b4         ls.c
0xbffff6b0         ls.xyz[2]
0xbffff6ac         ls.xyz[1]
0xbffff6a8         ls.xyz[0]
0xbffff6a4         3
0xbffff6a0         5
0xbffff69c         v0
0xbffff698         v1
0xbffff694         v2

A: struct color *
B: v2,v1,v0,5,3,ls,&rgb 
C: 0xbffff6d0
D: -4


6. 
from left to right top to bottom

part 1: 
(a)
4 - 4 - 4
16 - 64 - 16

(b)
1 - 1 - 1
4 - 64 - 4

part 2: 

(a)
4 - 4 - 4
16 - 16 - 64

(b) 
1 - 1 - 1 
16 - 4 - 16 


7:
Signaling: 0

Producer/Consumer: 
 Producer thread: swap P(mutex) and P(not_full)
 N, 0, 1

8.
1) a
2) b
3) e
4) c
5) e
6) c

9:

Part One:

Change

pid = waitpid(-1,&status,WNOHANG);

to

while((pid = waitpid(-1,&status,WNOHANG) > 0);

Part Two:

There are several solutions.  One possibility is to add
the following line to function echo:

pthread_detach(pthread_self());

One student pointed out that by having the parent call exit(0); after
reading end-of-file, it might termiante threads before they have
completed their tasks of printing out "ouch!".