9、数值的整数次方------------>剑指offer系列

  function Power(base, exponent) {
      if (exponent === 0) {
        return 1;
      } else {
        if (exponent > 0) {
          var result = 1;
          for (let i = 0; i < exponent; i++) {
            result *= base;
          }
          return result;
        } else if (exponent < 0) {
          var result = 1;
          for (let i = 0; i < Math.abs(exponent); i++) {
            result *= base;
          }
          return result ? 1 / result : false;
        }
      }
    }

const invalidFlag=false
function Power(base, exponent)
{
    // write code here
    if(base===0&&exponent<0)
    {
        invalidFlag=true;
        return 0;
    }
    const abs_exponent=exponent>0?exponent:-exponent;
    let result=PowerWithExponent(base, abs_exponent);
    if(exponent<0){
        return 1.0/result;
    }
    return result;
    
}
function PowerWithExponent(base, abs_exponent){
    if(abs_exponent===0)
        return 1;
    if(abs_exponent===1)
        return base;
    let result=PowerWithExponent(base,Math.floor(abs_exponent/2))
    result*=result;
    if(abs_exponent%2===1)
        result*=base;
    return result;
}