数组中的逆序列的错误编程小记 

 1 class Solution:
 2     def InversePairs(self, data):
 3         # write code here
 4         if not data:
 5             return 0
 6         tmp = [i for i in data]
 7         length = len(data) -1
 8         return (self.core(tmp, data, 0, length))%1000000007
 9     
10     def core(self, tmp, data, low, high):
11         if low >= high:
12             tmp[low] = data[low]
13             return 0
14         mid = (low+high)/2
15         left = self.core(self, data, tmp, low, mid)
16     #在定义函数的时候要加self， 在调用函数，函数前要加， 函数内部则不用加
17         right = self.core(data, tmp, (mid+1), high)
18         i = low
19         j = mid + 1
20         count = 0
21         idx = low
22         while i <= mid and j <= high:
23             if data[i] <= data[j]:
24                 i += 1
25         #i 是先自增还是先赋值， 顺序不同会导致list out of index
26                 tmp[idx] = data[i]
27             else:
28                 j += 1
29                 tmp[idx] = data[j]
30                 count += (mid - i + 1)
31             idx += 1
32         while i <= mid:
33             tmp[idx] = data[i]
34             i += 1
35             idx += 1
36         while j <= high:
37             tmp[idx] = data[j]
38             j += 1
39             idx +=1
40         return left + right + count

两点教训

posted @ 2018-08-09 16:42  幻影蝶之舞  阅读(93)  评论(0)    收藏  举报