题目
Given an array and a value, remove all instances of that value in place and return the new length.
The order of elements can be changed. It doesn't matter what you leave beyond the new length.
解题思路：
用两个指针，一个指向结果数组，一个遍历数组。
代码：
public int removeElement(int[] A, int elem) {
if (A.length == 0 || A == null)
return 0;
int i = 0;
int j = 0;
while (j < A.length) {
if (A[j] == elem)
j++;
else
A[i++] = A[j++];
}
return i;
}
