[leetcode刷题系列]Remove Element

- - 简单技巧，快排中有类似的技巧

class Solution {public:    int removeElement(int A[], int n, int elem) {        // Start typing your C/C++ solution below        // DO NOT write int main() function        int valid = -1;        for(int i = 0; i < n; ++ i)            if(A[i] != elem){                valid ++ ;                A[valid] = A[i];            }        return valid + 1;    }};