(算法分析Week3)Reverse Integer[Easy]

7. Reverse Integer

Description

Reverse digits of an integer.

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

Note:
The input is assumed to be a 32-bit signed integer. Your function should return 0 when the reversed integer overflows.

Solution

水题。位权概念不用多说了，思路就是每次取模，留下最低位，然后循环乘10。

Complexity analysis

O（n）,n为待逆序数的位数。

Code

class Solution {public:    int reverse(int x) {        long long result = 0;        int i = 0;        while(x != 0 ) {            result *= 10;            result += x %10;            x /= 10;            i++;        }        if (result > INT_MAX || result < INT_MIN)            result = 0;            //overflow        return result;    }};

Result