Question

如何用Python for循环语句，if语句 计算1-2+3-4+5......-99

Answer 1

sum=0
flag=1
for i in range(1,100):
    sum+=i*flag
    flag=-flag
print(sum)

最后那个-99应该是+99吧

Answer 2

total=0
for i in range(1,100):
	#奇数加
    if i%2!=0:
        total=total+i
    #偶数减
    elif i%2==0:
        total=total-1
print(a)

Answer 3

sum(( n*(-1,1)[n&1] for n in range(1,100) ))