27 Remove Element

27. Remove Element

1. Question

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-placewith O(1) extra memory.
The order of elements can be changed. It doesn't matter what you leave beyond the new length.
Example:
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Given nums = [3,2,2,3], val = 3,
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Your function should return length = 2, with the first two elements of nums being 2.
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2. Implementation

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public class Solution {
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public int removeElement(int[] nums, int val) {
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if (nums == null || nums.length == 0) {
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return 0;
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}
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int index = 0;
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for (int num : nums) {
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if (num != val) {
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nums[index++] = num;
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}
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}
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return index;
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}
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}
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3. Time & Space Complexity

时间复杂度O(n), 空间复杂度O(1)