7_ReverseInteger - a920604a/leetcode GitHub Wiki

---

title: 7. Reverse Integer

tags:
- Bit Manipulation - Math categories: leetcode comments: false

problem

Given a 32-bit signed integer, reverse digits of an integer.

solution

• 要注意是否會overflow，在每次將結果加到ret變數時都必須檢查是否overflow

option 1

class Solution {
public:
    int reverse(int x) {
        
        int ret = 0;
        while(x){
            if(abs(ret) > INT_MAX/10) return 0;
            ret = 10*ret + (x%10);
            x/=10;
        }
        return ret;
    }
};

analysis

• time complexity O(1)
• space complexity O(1)