12. 数值的整数次方

快速幂运算实现

最新推荐文章于 2024-04-07 18:08:16 发布

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/**
 * @Classname Solution
 * @Description TODO
 * @Date 2019/12/17 20:13
 * @Created by Cheng
 */
public class Solution {
    public double Power(double base, int exponent) {
        if (base == 0) {
            if (exponent >= 0)
                return 0;
            throw new IllegalArgumentException("invalid  input");
        } else {
            if (exponent == 0) {
                return 1;
            } else if (exponent > 0) {
                double ret = Power(base,exponent/2)*Power(base,exponent/2);
                if((exponent&1)==1)
                    ret *=base;
                return ret;
            } else {
                return 1 / Power(base, -exponent);
            }
        }
    }
}