leetcode1310

 1 class Solution:
 2     def xorQueries(self, arr: 'List[int]', queries: 'List[List[int]]') -> 'List[int]':
 3         n = len(arr)
 4         prefixsum = [arr[0]] * n
 5         res = []
 6         for i in range(1,n):
 7             prefixsum[i] = prefixsum[i-1] ^ arr[i]
 8 
 9         m = len(queries)
10         for i in range(m):
11             begin = queries[i][0]
12             end = queries[i][1]
13             if begin == 0:
14                 cur = prefixsum[end]
15             else:
16                 cur = prefixsum[end] ^ prefixsum[begin-1]
17             res.append(cur)
18         return res

Algorithm thinking: bit computing. The nature of the exclusive-OR operation are: x ^ x = 0, and x ^ 0 = x.

XOR array prefixsum order before Mr. Cheng.

For the closed interval [begin, end], only need to use a boundary position prefixsum corresponding to XOR.

If begin == 0, the calculation result is prefixsum [end];

If begin> 0, is calculated activation prefixsum [end] - prefixsum [begin-1].