计算1^2 - 2^2 + 3^2 - 4^2… 97^2 - 98^2 + 99^2

计算1^2 - 2^2 + 3^2 - 4^2… 97^2 - 98^2 + 99^2

def jicheng(num):

    if num%2 == 0:
        fuhao = -1
    else:
        fuhao = 1
    if num == 0:
        return 1
    else:
        return num * num + fuhao * jicheng(num - 1)
print(jicheng(99))