leetcode 9:Palindrome Number
2016-09-01 00:34
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题目:
Determine whether an integer is a palindrome. Do this without extra space.
想法:
题目说不能有额外的空间,其实意思是空间是O(1)的。所以不能将int类型转换为string类型再判断。我们的方案是每次首尾比较用div控制,还有就是负数不是回文数。
解答:
Determine whether an integer is a palindrome. Do this without extra space.
想法:
题目说不能有额外的空间,其实意思是空间是O(1)的。所以不能将int类型转换为string类型再判断。我们的方案是每次首尾比较用div控制,还有就是负数不是回文数。
解答:
class Solution { public: bool isPalindrome(int x) { if (x < 0) return false; int div = 1; while(x/div >= 10){ div *= 10; } while(x){ int l = x / div; int r = x % 10; if (l != r) return false; x = (x % div) / 10; div /= 100; } return true; } };
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