标签：turn || you ble com int start [] and
Given an array, rotate the array to the right by k steps, where k is non-negative.
Example 1:
Input:[1,2,3,4,5,6,7]and k = 3 Output:[5,6,7,1,2,3,4]Explanation: rotate 1 steps to the right:[7,1,2,3,4,5,6]rotate 2 steps to the right:[6,7,1,2,3,4,5]rotate 3 steps to the right:[5,6,7,1,2,3,4]
Example 2:
Input: [-1,-100,3,99] and k = 2
Output: [3,99,-1,-100]
Explanation:
rotate 1 steps to the right: [99,-1,-100,3]
rotate 2 steps to the right: [3,99,-1,-100]
Note:
in-place, O(1) extra space
先reverse前n-k个元素，再reverse后k个元素，再reverse整个数组
e.g. [1,2,3,4,5,6,7], k = 3 ：-> [4,3,2,1,5,6,7] -> [4,3,2,1,7,6,5] -> [5,4,7,1,2,3,4]
注意k有可能大于数组的长度，用mod找到最小的k
time: O(n), space: O(1)
class Solution { public void rotate(int[] nums, int k) { if(nums == null || nums.length == 0) return; int n = nums.length; k = k % n; reverse(nums, 0, n-1-k); reverse(nums, n-k, n-1); reverse(nums, 0, n-1); } private void reverse(int[] nums, int start, int end) { while(start <= end) { int tmp = nums[start]; nums[start] = nums[end]; nums[end] = tmp; start++;end--; } } }
标签：turn || you ble com int start [] and
原文地址：https://www.cnblogs.com/fatttcat/p/10090166.html
