Leetcode - Move Zeroes

Question

Given an array nums, write a function to move all 0’s to the end of it while maintaining the relative order of the non-zero elements.

For example, given nums = [0, 1, 0, 3, 12], after calling your function, nums should be [1, 3, 12, 0, 0].

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Note

1. You must do this in-place without making a copy of the array.
2. Minimize the total number of operations.

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Java Code

public void moveZeroes(int[] nums) {
    int len = nums.length;
    int i = 0;

    //遍歷數組前面連續的非零元素
    while(nums[i] != 0)
        if((++i) == len) return;

    //指針j用於依次遍歷數組的元素，指針i指向需要被覆蓋的元素
    //即把所有非零元素全部移動到數組前部，且按照原來的順序緊挨在一起
    int j = i;
    while(j < len) {
        if(nums[j] != 0)
            nums[i++] = nums[j];
        ++j;
    }

    //先得到數組中0的個數，再把數組後部置零，相當於把所有0後移
    int zeros = j - i;
    while(zeros > 0) {
        nums[len - zeros] = 0;
        --zeros;
    }   
}

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