[LeetCode] 283. Move Zeroes 移动零

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].

Note:

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

Credits:
Special thanks to @jianchao.li.fighter for adding this problem and creating all test cases.

把一个数组里所有的0都移到后面，不能改变非零数的相对位置关系，而且不能拷贝额外的数组。

要用替换法in-place，双指针来做，前面的指针指向处理过的最后一个非零数字， 后面一个指针向后扫，遇到非零数字，和前面指针所指数字交换位置，前面指针后移1位。

或者不交换只把非零的数字换到前面，最后子统一把后面的全部变成0。

Java: Time Complexity: O(n), Space Complexity: O(1)

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public class Solution {     public void moveZeroes(int[] nums) {         int index = 0;         for (int i = 0; i < nums.length; ++i) {             if (nums[i] != 0) {                 nums[index++] = nums[i];             }         }         for (int i = index; i < nums.length; ++i) {             nums[i] = 0;         }     } }

Python:

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class Solution(object):     def moveZeroes(self, nums):         """         :type nums: List[int]         :rtype: void Do not return anything, modify nums in-place instead.         """         pos = 0         for i in xrange(len(nums)):             if nums[i]:                 nums[i], nums[pos] = nums[pos], nums[i]                 pos += 1

C++:

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class Solution { public:     void moveZeroes(vector<int>& nums) {         int pos = 0;         for (auto& num : nums) {             if (num) {                 swap(nums[pos++], num);             }         }     } };

 

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[LeetCode] 27. Remove Element

 

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