Leetcode 246. Strobogrammatic Number

A strobogrammatic number is a number that looks the same when rotated 180 degrees (looked at upside down).

Write a function to determine if a number is strobogrammatic. The number is represented as a string.

For example, the numbers "69", "88", and "818" are all strobogrammatic.

题解：虽是简单题。但一些case也要留意。

class Solution {public:    bool isStrobogrammatic(string num) {        int len=num.size();        if(len==0) return true;        int l=0,r=len-1;        while(l<=r) {            if(l==r) {                if(num[l]=='0'||num[l]=='1'||num[l]=='8') return true;                else return false;            }            if(num[l]=='1') {                if(num[r]!='1') return false;            }            else if(num[l]=='6') {                if(num[r]!='9') return false;            }            else if(num[l]=='9') {                if(num[r]!='6') return false;            }            else if(num[l]=='8') {                if(num[r]!='8') return false;            }            else if(num[l]=='0') {                if(num[r]!='0') return false;            }            else return false;            l++;r--;        }        return true;    }};