用while循环处理1-100内之和，1-100内的所有奇数，1-100内所有偶数，1-2+3-4+...99的和

1-100内求和

count = 1
sum = 0
while count <= 100:
    sum = sum + count
    count +=1
print(sum)

1-100内的所有奇数

count = 1
while count < 100:
    if count % 2 != 0:
        print(count)
    count += 1

1-100内所有偶数

count = 1
while count < 100:
    if count % 2 == 0:
        print(count)
    count += 1

1-2+3-4...99的和

count = 1
sum = 0
while count <= 99:
    if count % 2 != 0:
        sum += count
    else:
        sum -= count
    count += 1
print(sum)