Added bit-manipulation and two-pointer

Author: Prashant Jain

src/in/knowledgegate/dsa/bitmanipulation/SingleNumber.java

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+package in.knowledgegate.dsa.bitmanipulation;
+
+/**
+ * Given a non-empty array of integers nums,
+ * every element appears twice except for one.
+ * Find that single one.
+ *
+ * You must implement a solution with a linear
+ * runtime complexity and use only constant extra
+ * space.
+ *
+ * Example 1:
+ * Input: nums = [2,2,1]
+ * Output: 1
+ *
+ * Example 2:
+ * Input: nums = [4,1,2,1,2]
+ * Output: 4
+ *
+ * Example 3:
+ * Input: nums = [1]
+ * Output: 1
+ *
+ * Constraints:
+ * 1 <= nums.length <= 3 * 104
+ * -3 * 104 <= nums[i] <= 3 * 104
+ * Each element in the array appears twice except
+ * for one element which appears only once.
+ */
+public class SingleNumber {
+  public int singleNumber(int[] nums) {
+    int num = 0;
+    for (int i = 0; i < nums.length; i++) {
+      num ^= nums[i];
+    }
+    return num;
+  }
+}

src/in/knowledgegate/dsa/twopointer/RemoveElement.java

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+package in.knowledgegate.dsa.twopointer;
+
+/**
+ * Given an integer array nums and an integer val,
+ * remove all occurrences of val in nums in-place.
+ * The relative order of the elements may be changed.
+ *
+ *
+ * Do not allocate extra space for another array.
+ * You must do this by modifying the input array
+ * in-place with O(1) extra memory.
+ *
+ *
+ * Example 1:
+ * Input: nums = [3,2,2,3], val = 3
+ * Output: 2, nums = [2,2,_,_]
+ * Explanation: Your function should return k = 2,
+ * with the first two elements of nums being 2.
+ * It does not matter what you leave beyond the
+ * returned k (hence they are underscores).
+ *
+ * Example 2:
+ * Input: nums = [0,1,2,2,3,0,4,2], val = 2
+ * Output: 5, nums = [0,1,4,0,3,_,_,_]
+ * Explanation: Your function should return k = 5,
+ * with the first five elements of nums containing
+ * 0, 0, 1, 3, and 4.
+ */
+public class RemoveElement {
+  public int removeElement(int[] nums, int val) {
+    int insertLoc = 0;
+    for (int i = 0; i < nums.length; i++) {
+      if (val != nums[i]) {
+        nums[insertLoc++] = nums[i];
+      }
+    }
+    return insertLoc;
+  }
+}