26. Remove Duplicates from Sorted Array

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 in place with constant memory.

For example,

Given input array 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.

解题思路：

利用数组有序的特点，标记index＝0，从下标1开始遍历数组，遇到与index下标不同的数字array[i]，index＝index＋1，此时index下标的数替换为array[i]。直到遍历结束，返回index＋1。

特别的，当数组为空时，直接返回0。

class Solution {
public:
int removeDuplicates(vector<int>& nums) {
if (nums.size() == 0) return 0;

int index = 0;
for (int i = 1; i < nums.size(); i++) {
if (nums[index] != nums[i]) {
nums[++index] = nums[i];
}
}
return index + 1;
}
};