[Java] Remove Element
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[Java] Remove Element
LeetCode Problem #27 🔗 LeetCode Link
Espeically, this problem is in the Must-do List for Interview Prep in Leetcode.
Description
Given an integer array nums and an integer val, remove all occurrences of val in nums in-place. The order of the elements may be changed. Then return the number of elements in nums which are not equal to val.
Consider the number of elements in nums which are not equal to val be k, to get accepted, you need to do the following things:
Change the array nums such that the first k elements of nums contain the elements which are not equal to val. The remaining elements of nums are not important as well as the size of nums.
Return k.
Example
- Input: nums = [3, 2, 2, 3], val = 3
- Output: 2, nums = [2, 2, _, _]
- Explanation: Your function should return k = 2, with the first two elements of nums being 2. It does not matter what you leave beyond the returned k (hence they are underscores).
My Solution
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class Solution {
public int removeElement(int[] nums, int val) {
int size = nums.length;
int leftIdx = 0;
int rightIdx = nums.length-1;
while (leftIdx < rightIdx) {
if (nums[leftIdx] == val && nums[rightIdx] != val) {
// swap
int temp = nums[leftIdx];
nums[leftIdx] = nums[rightIdx];
nums[rightIdx] = temp;
}
if (nums[leftIdx] != val) leftIdx++;
if (nums[rightIdx] == val) rightIdx--;
}
// count the number which is not val
for (int i = nums.length-1; i >= 0; --i) {
if (nums[i] == val) {
size--;
}
}
return size;
}
}