remove-element

【题目描述】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.
数组中与给定值相同的元素删除，在原数组上修改，返回值是最终元素个数。

【解题思路】idex记录数目，从头遍历，将与给定值相同的元素放到原数组的结尾，end始终指向最终数组的结尾

【考查内容】数组

class Solution {
public:
    int removeElement(int A[], int n, int elem) {
        if( n == 0 )
            return 0;
        int idx = 0;
        int end = n - 1;
        while( idx < end ){
            if( A[idx] != elem )
                ++idx;
            else{
                swap( A[idx], A[end] );
                --end;
            }
        }
        if( A[idx] != elem )
            return idx + 1;
        else
            return idx;
    }
};