Reverse Integer

要判断是否会溢出，这点注意一下例如1123456789 反转过来就会超int.

int reverse(int x) {
    int cur = abs(x);long long ans = 0;
    int result = 0;
    while(cur){
        result = result*10+cur%10;
        ans = ans*10+(long long)cur%10;
        cur/=10;
    }
    if(ans!=(long long )result) result = 0;
    return x<0?0-result:result;
}