数值的整数次方 牛客网 剑指Offer

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数值的整数次方 牛客网 剑指Offer

• 题目描述
• 给定一个double类型的浮点数base和int类型的整数exponent。求base的exponent次方

class Solution:
    #run:23ms memory:5728k
    def Power(self, base, exponent):
        flag = 0
        if base == 0:
            return False
        if exponent == 0:
            return 1
        if exponent < 0:
            flag = 1
        ret = 1
        absExponent = abs(exponent)
        ret = self.pow(base,absExponent)
        if flag == 1:
            ret = 1/ret
        return ret

    def pow(self,X,N):
        if N == 0:
            return 1
        if N == 1:
            return X
        if N % 2 == 0:
            return self.pow(X*X,N/2)
        else:
            return self.pow(X*X,N/2) * X

    #run:21ms memory:5856k
    def Power2(self,base,exponent):
        flag = 0
        if base == 0:
            return False
        if exponent == 0:
            return 1
        if exponent < 0:
            flag = 1
        ret = 1
        absExponent = abs(exponent)
        for i in range(absExponent):
            ret *= base
        if flag == 1:
            ret = 1/ret
        return ret