why does it work unexpectedly ?

Question

Please show me my mistake , for negative inputs , it does not output an expected value .

class Solution {
public:
double myPow(double x, int n) {

if(n==0){
return 1;

}

else if(n>0){

if(n%2==0){

double number = myPow(x,n/2);
return number*number;

}

else{

double number = myPow(x,n/2);
return x*number*number;

}
}

else if(n<0) {

if(n == -1){

return 1/x;
}
else{

double number = myPow(x,n/2);
double r = 1/number;
double r_x = 1/x;
double res = r*r;
double otherwise = r_x*res;

if(n%2==0){

return res;
}
else{

return otherwise;
}
}
}

}
};

Answer 1

x is 5 and n is -2

if (n < 0) // true
Then number = myPow(x, n/2) = 1/5
r = 1/number = 5
res = r*r = 25
if (n%2==0) //-2%2 == 0
Then return res = 25

Answer 2

Ore I got the point ... thank you so much .

Answer 3

What do you mean by unexpectedly?

Answer 4

Eashan Morajkar suppose that the inputs are 5 and -2 . It outputs 25 , while it should output 1/25 ..
the else if(n<0){
..
} part has some bugs..

Answer 5

So your code just finds the square root or square

Answer 6

Eashan Morajkar hmmm.. square ? I have actually made a power function which should execute in O(log(n)) ... Pow(x,n) = x^n .

Answer 7

Ali_combination then i might not be the right person because i haven't learned it in school yet, sorry for wasting your time

Answer 8

Eashan Morajkar no problem bro ... good luck