7. Reverse Integer

int reverse(int x){
    
    int val = 0;
    int flag = 1;
    if(x<0){
        flag = -1;
        if(x>-2147483648) x = -x;
    }
    int temp = 0;
    int coef = 0;
    int exp = 0;
    temp = x;
    for(exp=0;temp>0;exp++){
        temp /= 10;
    }
    if(exp>0) exp--;
    while(exp>=0){
        coef = x%10;
        x /= 10;
        val += coef*pow(10,exp);
        exp--;
    }

    if(flag == -1) val = -val;
    if(flag>0 && val<0) val = 0;
    if(flag<0 && val>0) val = 0;

    return val;
}