ARTS 第17周

package org.nocoder.leetcode.solution;

/**
 * 27.Remove Element
 *
 * Given an array nums and a value val, 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 1:
 *
 * Given nums = [3,2,2,3], val = 3,
 *
 * Your function should return length = 2, with the first two elements of nums being 2.
 *
 * It doesn't matter what you leave beyond the returned length.
 * Example 2:
 *
 * Given nums = [0,1,2,2,3,0,4,2], val = 2,
 *
 * Your function should return length = 5, with the first five elements of nums containing 0, 1, 3, 0, and 4.
 *
 * Note that the order of those five elements can be arbitrary.
 *
 * It doesn't matter what values are set beyond the returned length.
 * Clarification:
 *
 * Confused why the returned value is an integer but your answer is an array?
 *
 * Note that the input array is passed in by reference, which means modification to the input array will be known to the caller as well.
 *
 * Internally you can think of this:
 *
 * // nums is passed in by reference. (i.e., without making a copy)
 * int len = removeElement(nums, val);
 *
 * // any modification to nums in your function would be known by the caller.
 * // using the length returned by your function, it prints the first len elements.
 * for (int i = 0; i < len; i++) {
 *     print(nums[i]);
 * }
 * @author jason
 * @date 2018/10/28.
 */
public class RemoveElement {
    public static int removeElement(int[] nums, int val) {
        if(nums == null || nums.length == 0){
            return 0;
        }
        int len = 0;

        for (int i = 0; i < nums.length ; i++) {
            if(nums[i] != val){
                nums[len] = nums[i];
                len ++;
            }
        }
        return len;
    }

    public static void main(){
        int[] nums = new int[]{3, 2, 2, 3};
        int val = 2;
        removeElement(nums, val);
    }
}