7. Reverse Integer&&190. Reverse Bits

Reverse digits of an integer.

Example1: x = 123, return 321

Example2: x = -123, return -321
思路：并没有什么特殊的……用一个long int来防止溢出并检验溢出

class Solution {
public:
int reverse(int x) {

int n=0;
long int sum=0;
if(x<0){x=x*(-1);n=1;}
while(x!=0){
int r=x%10;
sum=sum*10+r;
x=x/10;
}
if(sum>2147483647||sum<-2147483647) return 0;
if(n)return (int)-sum;
return (int)sum;
}
};

Reverse Bits是相关的题目

Reverse bits of a given 32 bits unsigned integer.

For example, given input 43261596 (represented in binary as 00000010100101000001111010011100), return 964176192 (represented in binary as00111001011110000010100101000000).

Follow up:

If this function is called many times, how would you optimize it?
思路：化成二进制再传上去……可以看下discuss区，各种大神各种叼……感觉自己和人家有智商上的差距……