标签：
Problem Description:
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.
The following is the C++ implementation of the suggested solution using a look-up table (implemented as an unordered_map). It takes 0 ms. But, I wonder, are there any real applications of strobogrammatic numbers?
1 class Solution { 2 public: 3 bool isStrobogrammatic(string num) { 4 make_lut(); 5 int n = num.length(); 6 for (int l = 0, r = n - 1; l <= r; l++, r--) 7 if (lut.find(num[l]) == lut.end() || lut.find(num[r]) == lut.end() || lut[num[l]] != num[r]) 8 return false; 9 return true; 10 } 11 private: 12 unordered_map<char, char> lut; 13 void make_lut(void) { 14 lut[‘0‘] = ‘0‘; 15 lut[‘1‘] = ‘1‘; 16 lut[‘6‘] = ‘9‘; 17 lut[‘8‘] = ‘8‘; 18 lut[‘9‘] = ‘6‘; 19 } 20 };
[LeetCode] Strobogrammatic Number
标签：
原文地址：http://www.cnblogs.com/jcliBlogger/p/4708243.html
