leetcode 27:Remove Element

Given an array and a value, remove all instances of that value in place and return the new length.

Do not allocate extra space for another array, you must do this in place with constant memory.

The order of elements can be changed. It doesn’t matter what you leave beyond the new length.

Example:
Given input array nums = [3,2,2,3], val = 3

Your function should return length = 2, with the first two elements of nums being 2.

解题思路

利用两个指针 i,j: i向后扫描，只要i指向的当前元素不等于指定元素，则交换i,j指向的元素，j++.最后 ,所有指定的元素都被移动到数组后排，j指向指定元素的首位。

代码实现

public class Solution {    public int removeElement(int[] nums, int val) {        int j=0;        int length = nums.length;        for(int i = 0 ; i < length ; i++){            if(nums[i] != val){                nums[j++] = nums[i];            }        }        return j;    }}