add: Reverse Integer and Remove Nth Node From End of List

Author: hijiangtao

README.md

@@ -10,6 +10,7 @@ Progress: 20/
 |2|[Add Two Numbers](https://leetcode.com/problems/add-two-numbers/) | [JavaScript](./src/add-two-numbers/res.js)|Medium|
 |7|[Reverse Integer](https://leetcode.com/problems/reverse-integer/) | [JavaScript](./src/reverse-integer/res.js)|Easy|
 |13|[Roman to Integer](https://leetcode.com/problems/roman-to-integer/) | [JavaScript](./src/roman-to-integer/res.js)|Easy|
+|19|[Remove Nth Node From End of List](https://leetcode.com/problems/remove-nth-node-from-end-of-list/) | [JavaScript](./src/remove-nth-node-from-end-of-list/res.js)|Medium|
 |22|[Generate Parentheses](https://leetcode.com/problems/generate-parentheses/) | [JavaScript](./src/generate-parentheses/res.js)|Medium|
 |26|[Remove Duplicates from Sorted Array](https://leetcode.com/problems/remove-duplicates-from-sorted-array/) | [JavaScript](./src/remove-duplicates-from-sorted-array/res.js)|Easy|
 |66|[Plus One](https://leetcode.com/problems/plus-one/) | [JavaScript](./src/plus-one/res.js)|Easy|
@@ -21,6 +22,7 @@ Progress: 20/
 |182|[Duplicate Emails](https://leetcode.com/problems/duplicate-emails/) | [SQL](./src/duplicate-emails/res.txt)|Easy|
 |183|[Customers Who Never Order](https://leetcode.com/problems/customers-who-never-order/) | [SQL](./src/customers-who-never-order/res.txt)|Easy|
 |184|[Department Highest Salary](https://leetcode.com/problems/department-highest-salary/) | [SQL](./src/department-highest-salary/res.txt)|Medium|
+|190|[Reverse Bits](https://leetcode.com/problems/reverse-bits/) | [JavaScript](./src/reverse-bits/res.txt)|Easy|
 |196|[Delete Duplicate Emails](https://leetcode.com/problems/delete-duplicate-emails/) | [SQL](./src/delete-duplicate-emails/res.txt)|Easy|
 |197|[Rising Temperature](https://leetcode.com/problems/rising-temperature/) | [SQL](./src/rising-temperature/res.txt)|Easy|
 |342|[Power of Four](https://leetcode.com/problems/power-of-four/) | [JavaScript](./src/power-of-four/res.js)|Easy|

src/remove-nth-node-from-end-of-list/res.js

@@ -0,0 +1,50 @@
+// Given a linked list, remove the nth node from the end of list and return its head.
+
+// For example,
+
+//    Given linked list: 1->2->3->4->5, and n = 2.
+
+//    After removing the second node from the end, the linked list becomes 1->2->3->5.
+// Note:
+// Given n will always be valid.
+// Try to do this in one pass.
+
+/**
+ * res.js
+ * @authors Joe Jiang (hijiangtao@gmail.com)
+ * @date    2017-02-25 18:17:02
+ * @version $Id$
+ */
+
+/**
+ * Definition for singly-linked list.
+ * function ListNode(val) {
+ *     this.val = val;
+ *     this.next = null;
+ * }
+ */
+/**
+ * @param {ListNode} head
+ * @param {number} n
+ * @return {ListNode}
+ */
+let removeNthFromEnd = function(head, n) {
+    let fast = head,
+        slow = head;
+    
+    for (let i=0; i<n; i++) {
+        fast = fast.next;
+    }
+    
+    if (!fast) {
+        return head.next;
+    }
+    
+    while(fast.next) {
+        fast = fast.next;
+        slow = slow.next;
+    }
+    
+    slow.next = slow.next.next;
+    return head;
+};

src/reverse-bits/res.js

@@ -0,0 +1,35 @@
+// Reverse bits of a given 32 bits unsigned integer.
+
+// For example, given input 43261596 (represented in binary as 00000010100101000001111010011100), return 964176192 (represented in binary as 00111001011110000010100101000000).
+
+// Follow up:
+// If this function is called many times, how would you optimize it?
+
+/**
+ * res.js
+ * @authors Joe Jiang (hijiangtao@gmail.com)
+ * @date    2017-02-25 20:55:29
+ * @version $Id$
+ */
+
+/**
+ * @param {number} n - a positive integer
+ * @return {number} - a positive integer
+ */
+var reverseBits = function(n) {
+    let bits = 31,
+        divs = Math.pow(2, 31),
+        res = 0;
+    
+    for ( ; n !== 0; ) {
+        let judge = Math.floor(n/divs);
+        if (judge) {
+            res += Math.pow(2, 31-bits);
+        }
+        n = n%divs;
+        divs /= 2;
+        bits -= 1;
+    }
+    
+    return res;
+};