leecode (8) - move zero

Mobile zero

Description:

Given an array of nums, write a function to move all zeros to the end of the array while maintaining the relative order of non-zero elements.

Example:

Explain:

1. You must operate on the original array. You cannot copy additional arrays.
2. Minimize the number of operations.

Train of thought:

According to the topic, we move the element whose value is not 0 forward and the element whose value is 0 to the back. An array element subscript can be set, initialized to 0, traversing the array from the front to the back. When an element with a value of 0 is encountered, it is exchanged with the element corresponding to the subscript initialized to 0, and then the subscript is added with 1. After traversing, we will move the element with a value of not 0 to the front, and the element with a value of 0 will naturally be placed at the back.

The code is as follows:

import java.util.Arrays;

public class MoveZeroes {
    public static void moveZeroes(int[] nums) {
        if (nums == null || nums.length == 0 || nums.length == 1) {
            return ;
        }
        int index = 0;
        for (int i = 0; i < nums.length; i++) {
            if (nums[i] != 0) {
                int temp = nums[i];
                nums[i] = nums[index];
                nums[index++] = temp;
            }
        }
    }

    public static void main(String[] args) {
        int[] nums = {0,1,0,3,12};
        moveZeroes(nums);
        System.out.println(Arrays.toString(nums));
    }
}

Another way of writing:

This method is similar to the one just written. All the non-zero elements in the array are assigned to the leading element bits of the array in order, and the rest are assigned to 0 directly. In fact, compared with the above, there is an operation of 0 assignment, which is not so simple. We suggest the first one (laugh with tears). But I wrote it myself. Record it. Ha ha.

import java.util.Arrays;

public class MoveZeroes {
    public static void moveZeroes(int[] nums) {
        if (nums == null || nums.length == 0 || nums.length == 1) {
            return ;
        }
        int index = 0;
        for (int i = 0; i < nums.length; i++) {
            if (nums[i] != 0) {
                nums[index] = nums[i];
                ++index;
                /*
                nums[index] = nums[i];
                ++index;
                These two sentences can be abbreviated as:
                nums[index++] = nums[i]; Simplify a little
                */
            }
        }
        for (int i = index; i < nums.length; i++) {
            nums[i] = 0;
        }
    }

    public static void main(String[] args) {
        int[] nums = {0,1,0,3,12};
        moveZeroes(nums);
        System.out.println(Arrays.toString(nums));
    }
}