283. Move Zeros

Given an arraynums, write a function to move all0's to the end of it while maintaining the relative order of the non-zero elements.

For example, givennums = [0, 1, 0, 3, 12], after calling your function,numsshould be[1, 3, 12, 0, 0].

Note:

1. You must do this in-place without making a copy of the array.

2. Minimize the total number of operations.

Credits: Special thanks [e-mail]for adding this problem and creating all test cases.

FB Followup: 输入是一个array, 有正数和负数，题目要求将正数移动到一侧，负数移动到另一侧。

Thoughts:

Having an pointer to keep track of non-zeros and replace the original value in the array then pad the rest of space with 0

Code

class Solution {
public:
    void moveZeroes(vector<int>& nums) {
        int j = 0;
        for(int i = 0 ; i < nums.size(); i++){
            if(nums[i]!= 0) nums[j++] = nums[i]; 
        }

        for(; j < nums.size();j++){
            nums[j] = 0;
        }
    }
};

FollowUp:

'''Ask if there is 0 in the array!'''
def move(arr): # with/ without 0
    i, j = 0, len(arr) - 1
    while True:
        while i <= j and arr[i] <= 0 : i+= 1
        while j >= i and arr[j] >= 0 : j-= 1
        if i > j: break
        arr[i], arr[j] = arr[j], arr[i]
    print(arr)