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1 # 求1-2+3-4+5.....99的所有数的和（含等式）
2 s = ""
3
4 sum = 0
5 start = 1
6
7 while start < 100:
8 temp = start % 2
9 if temp == 1:
10 if start == 1:
11 s = str(start)
12 else:
13 s = s + "+" + str(start)
14 sum = sum + start
15 else:
16 s = s + "-" + str(start)
17 sum = sum - start
18 start += 1
19
20 print(s)
21 print(start)
22
23
24
25 # 求1-2+3-4+5.....99的所有数的和（不含等式）
26 sum = 0
27 start = 1
28
29 while start < 100:
30 temp = start % 2
31 if temp == 1:
32 sum = sum + start
33 else:
34 sum = sum - start
35 start += 1
36
37 print(sum)
38 print(start)
