LeetCode--Reverse Integer (Cpp,Java,Python)

Reverse Integer

 

Total Accepted: 21990 Total
Submissions: 55259

Reverse digits of an integer.
Example1: x = 123, return 321
Example2: x = -123, return -321
click to show spoilers.

Have you been asked this question in an interview?

解题思路

注意负数和00的处理：

例如:

-2345

-23000

4

-3

0

源代码：

JAVA 源代码：

public class Solution {
public long reverse(int x) {
String str = String.valueOf(x);
StringBuilder sb=new StringBuilder();
boolean flag=true;
for( int i=str.length()-1; i>0; --i){
if (flag==true && str.charAt(i) == '0' ){
continue;
}else{
flag=false;
}
sb.append(str.charAt(i));
}
if(str.charAt(0)== '-'){
sb.insert(0, '-');
}else{
sb.append(str.charAt(0));
}
return Long.valueOf(sb.toString());
}
}

C++ 源代码：

class Solution {
public:
int reverse(int x) {
int r = 0;
for( ; x ; x/=10){
r= r*10 + x%10;
}
return r;
}
};

Python代码

（第一个python练习代码）

class Solution:
# @return an integer
def reverse(self, x):
s=''
ix = 0
x = str(x)
if x[0] == '-':
s += x[0]
ix = 1
beg=len(x)-1
while (x[beg] == '0' and beg > 0):
beg -= 1

if ix == 0 :
s += x[beg::-1]
else:
s += x[beg:0:-1]
return int(s)