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.

從頭開始遍歷，如果碰到一個指定元素，就和末尾的一個非指定元素的位置交換。

這種類型的題目 沒太大的難度 儘量寫得簡潔並且bug free

各種循環的終止條件判斷陷阱很多

public class Solution {
    public int removeElement(int[] A, int elem) {
        int span = 1;
        for(int i=0;i<=A.length-span;i++){
            if(A[i]==elem){
                while(A[A.length-span]==elem&&A.length-span>i){
                    span++;
                }
                int temp = A[A.length-span];
                A[A.length-span]=A[i];
                A[i] = temp;
                span++;
            }
        }
        return A.length-span+1;
    }
}