27. Remove Element(C++/Java)

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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.

C++ ：
代码1：

class Solution {
public:
    int removeElement(vector& nums, int val) {
        int index = 0;
        for (int i = 0; i < nums.size(); ++i) {
            if (nums[i] != val) {
                nums[index++] = nums[i];
            }
        }
        return index;
    }
};

代码2：

class Solution {
public:
    int removeElement(vector& nums, int val) {
        return distance(nums.begin(), remove(nums.begin(), nums.end(), val));
    }
};

Java：

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