add 026

Author: andavid

note/026/README.md

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+# [Remove Duplicates from Sorted Array][title]
+
+## Description
+
+Given a sorted array, remove the duplicates in-place such that each element appear only once and return the new length.
+
+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:**
+
+```text
+Given nums = [1,1,2],
+
+Your function should return length = 2, with the first two elements of nums being 1 and 2 respectively.
+It doesn't matter what you leave beyond the new length.
+```
+
+## 思路
+
+题意是让你从一个有序的数组中移除重复的元素，并返回之后数组的长度。
+此外，特别要注意，需要修改原数组。
+
+判断长度小于等于 1 的话直接返回原长度即可，否则的话遍历一遍数组，用一个 tail 变量指向新的数组尾部，如果后面的元素和前面的元素不同，就让后面的元素写到 tail 所指数组元素，然后 tail 变量加一，最后返回 tail 即可。
+
+## [完整代码][src]
+
+```Java
+class Solution {
+    public int removeDuplicates(int[] nums) {
+        int len = nums.length;
+        if (len <= 1) return len;
+
+        int tail = 1;
+        for (int i = 1; i < len; i++) {
+            if (nums[i] != nums[i - 1]) {
+                nums[tail++] = nums[i];
+            }
+        }
+
+        return tail;
+    }
+}
+```
+
+[title]: https://leetcode.com/problems/remove-duplicates-from-sorted-array
+[src]: https://github.com/andavid/leetcode-java/blob/master/src/com/andavid/leetcode/_026/Solution.java

src/com/andavid/leetcode/_026/Solution.java

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+package com.andavid.leetcode._026;
+
+public class Solution {
+    public int removeDuplicates(int[] nums) {
+        int len = nums.length;
+        if (len <= 1) return len;
+
+        int tail = 1;
+        for (int i = 1; i < len; i++) {
+            if (nums[i] != nums[i - 1]) {
+                nums[tail++] = nums[i];
+            }
+        }
+
+        return tail;
+    }
+
+    public static void main(String[] args) {
+        Solution solution = new Solution();
+        int[] nums = {1, 1, 2, 3, 3, 3};
+
+        int len = solution.removeDuplicates(nums);
+        System.out.println("length = " + len);
+
+        for (int i = 0; i < len; i++) {
+            System.out.print(nums[i] + (i == len - 1 ? "" : ", "));
+        }
+    }
+}