diff --git a/.idea/compiler.xml b/.idea/compiler.xml
new file mode 100644
index 0000000..ec58ff0
--- /dev/null
+++ b/.idea/compiler.xml
@@ -0,0 +1,11 @@
+
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\ No newline at end of file
diff --git a/.idea/copyright/profiles_settings.xml b/.idea/copyright/profiles_settings.xml
new file mode 100644
index 0000000..e7bedf3
--- /dev/null
+++ b/.idea/copyright/profiles_settings.xml
@@ -0,0 +1,3 @@
+
+
+
\ No newline at end of file
diff --git a/.idea/encodings.xml b/.idea/encodings.xml
new file mode 100644
index 0000000..97626ba
--- /dev/null
+++ b/.idea/encodings.xml
@@ -0,0 +1,6 @@
+
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\ No newline at end of file
diff --git a/.idea/misc.xml b/.idea/misc.xml
new file mode 100644
index 0000000..401d515
--- /dev/null
+++ b/.idea/misc.xml
@@ -0,0 +1,4 @@
+
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+
\ No newline at end of file
diff --git a/.idea/uiDesigner.xml b/.idea/uiDesigner.xml
new file mode 100644
index 0000000..e96534f
--- /dev/null
+++ b/.idea/uiDesigner.xml
@@ -0,0 +1,124 @@
+
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+ -
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+ -
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+ -
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diff --git a/.idea/workspace.xml b/.idea/workspace.xml
new file mode 100644
index 0000000..377f290
--- /dev/null
+++ b/.idea/workspace.xml
@@ -0,0 +1,944 @@
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\ No newline at end of file
diff --git a/java/PlusOne.java b/java/PlusOne.java
new file mode 100644
index 0000000..85c2356
--- /dev/null
+++ b/java/PlusOne.java
@@ -0,0 +1,29 @@
+public class Solution {
+ public int[] plusOne(int[] digits) {
+ int length = digits.length;
+ int sum;
+ int one = 1;//plus one, it contains carry as well
+ HashMap map = new HashMap<>();
+ for (int i = length - 1; i >= 0; i--) {//from end to top
+ sum = one + digits[i];//add the number i level digit with the carry
+ one = sum / 10;//get the new carry
+ map.put(i, sum % 10);//put the finally new digit to map
+ }
+ if (one > 0) {
+ int[] ret = new int[map.size() + 1];
+ ret[0] = one;
+ for (int j = 0; j < map.size(); j++) {
+ ret[j+1] = map.get(j);
+ }
+ return ret;
+ } else {
+ int[] ret = new int[map.size()];
+ for (int j = 0; j < map.size(); j++) {
+ ret[j] = map.get(j);
+ }
+ return ret;
+ }
+
+
+ }
+}
\ No newline at end of file
diff --git a/java/RemoveDuplicates.java b/java/RemoveDuplicates.java
new file mode 100644
index 0000000..cd9704d
--- /dev/null
+++ b/java/RemoveDuplicates.java
@@ -0,0 +1,36 @@
+/**
+ * Created by sooglejay on 16/1/12.
+ */
+public class RemoveDuplicates {
+ public static void main(String[] args) {
+ System.out.print(removeDuplicates(new int[]{1, 1, 1, 1, 1, 1, 1, 2, 2, 3, 3, 3, 4
+ }));
+
+ }
+
+ /***
+ * 使用两个下标,i,j,i做遍历,j做新数组长度
+ * @param nums
+ * @return
+ */
+ public static int removeDuplicates(int[] nums) {
+ int n;
+ if ((n = nums.length) < 1) {
+ return n;
+ }
+ int j = 0;
+ int num = 0;
+ for (int i = 1; i < n; i++) {
+ if (nums[j] == nums[i]) {
+ num++;
+ if (num < 2) {//超过两个就不管了,
+ nums[++j] = nums[i];
+ }
+ } else {//把剩下的都往前面搬
+ nums[++j] = nums[i];
+ num = 0;
+ }
+ }
+ return j + 1;
+ }
+}
diff --git a/java/RemoveValue.java b/java/RemoveValue.java
new file mode 100644
index 0000000..7ea2311
--- /dev/null
+++ b/java/RemoveValue.java
@@ -0,0 +1,30 @@
+/**
+ * Created by sooglejay on 16/1/12.
+ */
+public class RemoveValue {
+ public static void main(String args[]) {
+ System.out.print(removeElement(new int[]{4, 5}, 4));
+ }
+
+ /**
+ * 删除数组中的特定值,使用变量newLength来计算新数组的长度
+ * @param nums
+ * @param val
+ * @return
+ */
+ public static int removeElement(int[] nums, int val) {
+ int length;
+ if ((length = nums.length) < 1) {
+ return length;
+ }
+ int newLength = 0;
+ for (int i = 0; i < length; i++) {
+ if (nums[i] == val) {
+ continue;
+ }
+ nums[newLength] = nums[i];
+ newLength++;
+ }
+ return newLength;
+ }
+}
diff --git a/java/ReverseLink.java b/java/ReverseLink.java
new file mode 100644
index 0000000..7a83401
--- /dev/null
+++ b/java/ReverseLink.java
@@ -0,0 +1,100 @@
+/**
+ * Created by sooglejay on 16/1/16.
+ */
+public class Solution {
+ //Assume that we have linked list 1 → 2 → 3 → Ø, we would like to change it to Ø ← 1 ← 2 ← 3
+
+ /**
+ * efficient solution
+ *
+ * @param head
+ * @return
+ */
+ public ListNode reverseList1(ListNode head) {
+ if (head == null || head.next == null) return head;
+ ListNode p = reverseList1(head.next);
+ head.next.next = head;
+ head.next = null;
+ return p;
+ }
+
+ /**
+ * efficient solution
+ *
+ * tips:
+ * While you are traversing the list,
+ * change the current node's next pointer to point to its previous element
+ * @param head
+ * @return
+ */
+ public ListNode reverseList2(ListNode head) {
+ ListNode prev = null;
+ ListNode curr = head;
+ while (curr != null) {
+ ListNode nextTemp = curr.next;
+ curr.next = prev;
+ prev = curr;
+ curr = nextTemp;
+ }
+ return prev;
+ }
+
+ /**
+ * inefficient solution
+ *
+ * @param head
+ * @return
+ */
+ public static ListNode reverseList3(ListNode head) {
+ int size = 0;
+ ListNode tempNode = head;
+ //get the size of the list
+ while (tempNode != null) {
+ size++;
+ tempNode = tempNode.next;
+ }
+ if (size < 2) {
+ return head;
+ }
+ //data array to store each value of each node
+ int data[] = new int[size];
+ while (head != null) {
+ data[--size] = head.val;//store array elements from end to start
+ head = head.next;
+ }
+
+ ListNode footer = new ListNode(data[0]);
+ head = footer;
+ //recreate a new list
+ for (int j = 1; j < data.length; j++) {
+ ListNode node = new ListNode(data[j]);
+ footer.next = node;
+ footer = footer.next;
+ }
+ return head;
+ }
+
+}
+
+/**
+ * Created by sooglejay on 16/1/16.
+ */
+private static class ListNode {
+
+ int val;
+ ListNode next;
+
+ ListNode(int x) {
+ val = x;
+ }
+
+ @Override
+ public String toString() {
+ return "ListNode{" +
+ "val=" + val +
+ ", next=" + next +
+ '}';
+ }
+
+
+}