LeetCode move zeroes
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.
Analysis
We can use a pointer zeroIndex to always point to the index of the first 0. We scan the array, if we encounter a non-zero element, we exchange it with the first 0 that was pointed by zeroIndex, and increase the zeroIndex by 1. This idea has been applied to solve the color sort problem and remove elements problem.
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public class Solution { void swap(int[] nums, int i, int j){ int tmp = nums[i]; nums[i] = nums[j]; nums[j] = tmp; } public void moveZeroes(int[] nums) { int zeroIndex = 0; for(int i = 0; i < nums.length; i++) { if (nums[i] != 0) { swap(nums, i, zeroIndex); zeroIndex++; } } } } |
