NQueen.cpp : use Hill-Climbing Algorithm for eight queens.
evaluation function is calculate slope. time complex=O(n^2)
if local optimum than restart.

n	execution time	restart times	one epoch execution time
8	0.01334s	1	0.00667s
10	0.06260s	17	0.00347s
20	0.20403s	19	0.01020s
30	1.48939s	45	0.03309s
40	14.16768s	146	0.09637s
50	21.68516s	80	0.26771s
100	966.15776s	111	8.62640s

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fast_version.cpp : use Hill-Climbing Algorithm for eight queens, but is unstable, maybe restart many times.
evaluation function is calculate slope. time complex=O(n)
if local optimum than restart.

n	execution time	restart times	one epoch execution time
8	0.0074s	30	0.000238s
10	0.0048s	21	0.000218s
20	0.0340s	79	0.000425s
30	0.0833s	79	0.001041s
40	0.1299s	70	0.001855s
50	0.7567s	376	0.002007s
100	12.0820s	815	0.014806s
200	238.0028s	2080	0.114369s
300	1653.6015s	3916	0.422160s

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one epoch execution time = execution time / (restart times + 1)

table not so precise.
have lucky and computer performance affect.

	test computer
cpu	i7-3370 3.40GHz
ram	32GB

use visual studio release to compile.