27. Remove Element 移除元素

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 by modifying the input array in-place with O(1) extra memory.

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

Example:

Given nums = [3,2,2,3], val = 3,

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

Difficulty: Easy

这道题让我们移除数组中与给定的数相同的元素,并返回新的数组的长度.我们可以用一个变量来计数,然后遍历数组,如果当前位置和所给的值不同,就把计数变量位置处的数赋值为当前变量,并将计数变量加1.

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