leetcode 27 Remove Element

Remove Element:题目链接

方法1：双指针之快慢指针

import java.util.Arrays;

public class Solution1 {
    // 时间复杂度 O(N)   空间复杂度O(1)   双指针
    public static int removeElement(int[] nums, int val) {
        int slow = 0;                     // 存放不为val元素 区间[0, slow)
        for (int fast = 0; fast < nums.length; ++fast) {
            if (val != nums[fast]) {
                nums[slow++] = nums[fast];
            }
        }
        return slow;
    }

    public static void main(String[] args) {
        int[] nums = {0, 1, 2, 2, 3, 0, 4, 2};
        int val = 2;
        System.out.println(removeElement(nums, val));
        System.out.println(Arrays.toString(nums));
    }
}

方法2：双指针之对撞指针

void swap(int * nums, int i, int j){
    int temp = nums[i];
    nums[i] = nums[j];
    nums[j] = temp;
}

int removeElement(int* nums, int numsSize, int val){
    int i = 0, j = numsSize -1;
    while (i <= j) {
        if (nums[i] == val) {
            swap(nums, i, j);
            j--;
        }else{
            i++;
        }
    }
    return i;
}

ps：源代码链接