27. Remove Element

Given an array and a value, remove all instances of that value in place and return the new length.

给定一个数组和一个值，删除该值的所有实例，并返回新的长度。

Do not allocate extra space for another array, you must do this in place with constant memory.

The order of elements can be changed. It doesn’t matter what you leave beyond the new length.

元素的顺序可以被改变，也不关心最终的数组长度。

Example:

Given input array nums = [3,2,2,3], val = 3

Your function should return length = 2, with the first two elements of nums being 2.

Hint:

Try two pointers.

Did you use the property of “the order of elements can be changed”?

What happens when the elements to remove are rare?

利用上个题 283. Move Zeroes大神的思路，完美解决

class Solution {
public:
int removeElement(vector<int>& v, int val) {

int j=0;
for(int i=0; i<v.size(); i++)
{
if(v[i] != val)
{
v[j++]=v[i];
}
}
return j;
}
};