Reverse Integer

Author: w2xi

README.md

@@ -4,5 +4,6 @@
 |:---:|:---:|:---:|:---:|
 |1|[两数之和](https://leetcode-cn.com/problems/two-sum/)|[JavaScript](./algorithms/two-sum.js)|Easy|
 |2|[两数相加](https://leetcode-cn.com/problems/add-two-numbers/)|[JavaScript](./algorithms/add-two-numbers.js)|Medium|
+|7|[整数反转](https://leetcode-cn.com/problems/reverse-integer/)|[JavaScript](./algorithms/reverse-integer.js)|Medium|
 |9|[回文数](https://leetcode-cn.com/problems/palindrome-number/)|[JavaScript](./algorithms/palindrome-number.js)|Easy|
 |14|[最长公共前缀](https://leetcode-cn.com/problems/longest-common-prefix/)|[JavaScript](./algorithms/longest-common-prefix.js)|Easy|

algorithms/reverse-integer.js

@@ -0,0 +1,28 @@
+/**
+ * @param {number} x
+ * @return {number}
+ */
+var reverse = function (x) {
+  const isNegtive = x < 0;
+  let sum = 0;
+
+  if (x === 0) {
+    return 0;
+  }
+
+  x = Math.abs(x);
+
+  while (x) {
+    let t = x % 10;
+    sum = t + sum * 10;
+    x = Math.floor(x / 10);
+  }
+
+  sum = isNegtive ? -sum : sum;
+
+  if (sum < -Math.pow(2, 31) || sum > Math.pow(2, 31) - 1) {
+    return 0;
+  }
+
+  return sum;
+};