9. Palindrome Number
Posted dysjtu1995
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Problem:
Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward.
Example 1:
Input: 121
Output: true
Example 2:
Input: -121
Output: false
Explanation: From left to right, it reads -121. From right to left, it becomes 121-. Therefore it is not a palindrome.
Example 3:
Input: 10
Output: false
Explanation: Reads 01 from right to left. Therefore it is not a palindrome.
Follow up:
Coud you solve it without converting the integer to a string?
思路：
将整数由低位到高位依次压入数组中,然后比较前一半和后一半的值即可。
Solution (C++):
bool isPalindrome(int x) {
if (x < 0) return false;
if (x < 10) return true;
vector<int> vec{};
while (x/10) {
vec.push_back(x%10);
x /= 10;
if (x < 10) { vec.push_back(x); break; }
}
bool is_pal = true;
for (int i = 0; i <= (vec.size()-1) / 2; ++i) {
if (vec[i] != vec[vec.size()-1-i]) {
is_pal = false;
break;
}
}
return is_pal;
}
性能：
Runtime: 44 ms??Memory Usage: 9.5 MB
思路：
Solution (C++):
性能：
Runtime: ms??Memory Usage: MB
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