solutions to 4.38, 4.39 and 4.40

[sicp.git] / src / sicp / ex4_39.rkt

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+#lang racket
+
+#|
+
+There are 5*5*5*5*5 possibilities. The order won't affect the results. 
+But it will affect time. The various 'require' or 'assert' statements
+restrict the number of options and the possibility tree.
+ 
+Let us look at the statements now.
+
+1.    (assert (distinct? (list baker cooper fletcher miller smith)))
+2.    (assert (not (= baker 5)))
+3.    (assert (not (= cooper 1)))
+4.    (assert (not (= fletcher 5)))
+5.    (assert (not (= fletcher 1)))
+6.    (assert (> miller cooper))
+7.    (assert (not (= (abs (- fletcher cooper)) 1)))
+
+If we look the constraints in isolation, 
+
+constraint #1, will have 5*4*3*2*1 = 120 successes.
+constraint #2 will have 5*5*5*5*4  = 2400 successes.
+
+When they are put together, let us say #1 and then #2, then we have
+#1 executing for 5^5 times resulting in 120 successes and so #2 executing for 120 times.
+
+If we reverse #2 and #1, then we have #2 executing for 5^5 times giving 2400 possible 
+values and so #1 executes for 2400 times.
+
+So, if any condition takes more time to execute, then these numbers will be an effect, so
+order will affect the execution times.
+
+|#
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