LeetCode:Reverse Integer

Reverse digits of an integer.

Example1: x = 123, return 321
Example2: x = -123, return -321

class Solution {
public:
    int reverse(int x){
        int num[100],y=0,i,j;
        if(x<0)
        {
            num[0]=1;
            x=-x;
        }
        for(i=1;x>0;i++)
        {
            num[i]=x%10;
            x/=10;
        }
        for(j=1;j<i;j++)
        {
            y+=num[i-j]*pow(10,j-1);
        }
        y=(num[0]==1?-y:y);
        return y;
    }
};