Remove Element

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.

第一遍：

 1 public class Solution {
 2     public int removeElement(int[] A, int elem) {
 3         // Note: The Solution object is instantiated only once and is reused by each test case.
 4         int start = 0;
 5         for(int i = 0; i < A.length; i ++){
 6             if(A[i] != elem){
 7                 A[start ++] = A[i];
 8             }
 9         }
10         return start;
11     }
12 }

第三遍：

 1 public class Solution {
 2     public int removeElement(int[] A, int elem) {
 3         if(A == null || A.length == 0) return 0;
 4         int len = -1;
 5         for(int i = 0; i < A.length; i ++){
 6             if(A[i] != elem){
 7                 len ++;
 8                 A[len] = A[i];
 9             }
10         }
11         return len + 1;
12     }
13 }