Add documentation to 75.\nAdd solutions to 75 and 76.\nAdd templates till problem 85.

python/e075.py

@@ -95,6 +95,22 @@ def dicksons_method_efficient(r):
 
 
 def euler_075():
+    """
+    We are using Dickson's method to get all Pythagorean triples.  The
+    challenge is that this method requires finding the divisors for a
+    given r. To make it more efficient we stop iterating after the
+    perimeter exceeds the threshold L_max for any given r.
+    In addition we found a r_max of 258000 empirically.
+    This runs for 15 minutes with cpython and in under 5 minutes in pypy.
+    It would have been better to use a generator function that finds native
+    solutions and then extrapolate with factors k in range(2, 1500000)
+    while L < L_max.
+
+    https://en.wikipedia.org/wiki/Formulas_for_generating_Pythagorean_triples#Dickson's_method   
+
+    XXX: Can be strongly optimized.
+    """
+
     r_max = 258000
     perimeter_counts = {}
 
@@ -116,4 +132,4 @@ def euler_075():
 
 if __name__ == "__main__":
     print("e075.py: " + str(euler_075()))
-    # assert(euler_075() == 0)
+    assert(euler_075() == 161667)