LeetCode Reverse Integer

递归主要有两个点，一个是它递归的过程是怎么样的，一个就是递归的边界。

#include "pch.h"
#include <iostream>
using namespace std;
class Solution {
    typedef long long LL;
    LL ret = 0;
    bool isOverFlow = false;
public :
    int reverse(LL x) {
        if (x == 0 || isOverFlow) {
            return 0;
        }
        LL value = abs(x);
        ret = ret * 10 + value % 10;
        if (ret>INT_MAX) {
            isOverFlow = true;
        }
        reverse(x/10);
        return isOverFlow=true?0:(x>0?ret:-ret);
    }
};

#include "pch.h"
#include <iostream>
using namespace std;
class Solution {
    typedef long long LL;
    LL ret = 0;
    bool isOverFlow = false;
public :
    int reverse(LL x) {
        /*
        if (x == 0 || isOverFlow) {
            return 0;
        }
        LL value = abs(x);
        ret = ret * 10 + value % 10;
        if (ret>INT_MAX) {
            isOverFlow = true;
        }
        reverse(x/10);
        return isOverFlow=true?0:(x>0?ret:-ret);
        */
        LL value = abs(x);
        while (value!=0) {
            if (x == 0 || isOverFlow == true) {
                return 0;
            }
            ret = ret*10+value % 10;
            if (ret > INT_MAX) {
                isOverFlow = true;
                return 0;
            }
            value = value / 10;
        }
        return isOverFlow ? 0 : (x > 0 ? ret : -ret);
    }
};