@@ -81,3 +81,60 @@ var twoSum = function (nums, target) {
8181 }
8282};
8383```
84+ 85+ ### Given an integer x, return true if x is palindrome integer.
86+ 87+ An integer is a palindrome when it reads the same backward as forward.
88+ 89+ For example, 121 is a palindrome while 123 is not.
90+ 91+ Example 1:
92+ 93+ Input: x = 121
94+ Output: true
95+ Explanation: 121 reads as 121 from left to right and from right to left.
96+ Example 2:
97+ 98+ Input: x = -121
99+ Output: false
100+ Explanation: From left to right, it reads -121. From right to left, it becomes 121-. Therefore it is not a palindrome.
101+ Example 3:
102+ 103+ Input: x = 10
104+ Output: false
105+ Explanation: Reads 01 from right to left. Therefore it is not a palindrome.
106+ 107+ Constraints:
108+ 109+ -231 <= x <= 231 - 1
110+ 111+ ### Solution 1
112+ 113+ The space complexity for this solution is O(N).
114+ 115+ The time complexity for this solution is O(N).
116+ 117+ ``` js
118+ var isPalindrome = function (x ) {
119+ let splitNumber = x .toString ().split (" "
120+ let reverseNumberArr = [];
121+ for (let i = splitNumber .length ; i > - 1 ; i-- ) {
122+ if (! isNaN (splitNumber[i])) {
123+ reverseNumberArr .push (splitNumber[i]);
124+ }
125+ }
126+ return reverseNumberArr .join (" " === x;
127+ };
128+ ```
129+ 130+ ### Solution 2
131+ 132+ The space complexity for this solution is a constant O(1).
133+ 134+ The time complexity for this solution is also O(1).
135+ 136+ ``` js
137+ var isPalindrome = function (x ) {
138+ return x .toString () === x .toString ().split (" " reverse ().join (" "
139+ };
140+ ```
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