SRM596 DIV2 500

动态规划的题目

 1 class ColorfulRoad:
 2     def getMin(self, road):
 3         a = [None] * len(road)
 4         a[0] = 0
 5         for i in range(0, len(road)-1):
 6             if a[i] != None:
 7                 for j in range(i+1, len(road)):
 8                     if self.judgeValid(road[i], road[j]):
 9                         cost = a[i] + (j-i) ** 2
10                         if a[j] == None:
11                             a[j] = cost
12                         else:
13                             a[j] = min(a[j], cost)
14                         
15         if a[len(road)-1] == None:
16             return -1
17         else:
18             return a[len(road)-1]
19     
20     def judgeValid(self, fromch, toch):
21         step = ['R', 'G', 'B']
22         i = step.index(fromch)
23         return toch == step[(1+i)%3]
24                 
25                 
26 # test
27 o = ColorfulRoad()
28 
29 
30 # test case
31 assert(o.getMin('RGGGB') == 8)
32 
33 print('ok')
34 
35
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posted @ 2013-11-04 21:41  valaxy  阅读(131)  评论(0)    收藏  举报