p189

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LeetCode p189 Rotate Array 题解

1.题目：

Rotate an array of n elements to the right by k steps.

For example, with n = 7 and k = 3, the array [1,2,3,4,5,6,7] is rotated to [5,6,7,1,2,3,4].

题意：

输入一个数组，输入一个数字K，将数组末尾的K个数放到数组前面来。
如1234567 输入 3
输出567 1234

2.解题思路:

把数组分两段1234 567
分别反转 4321 765
整体反转 567 1234

3.代码

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public class Solution {
    public void rotate(int[] nums, int k) {
        k = k % nums.length; // 整数倍等于无操作
        reverse(nums, 0, nums.length - 1 - k);
		reverse(nums, nums.length - k, nums.length - 1);
		reverse(nums, 0, nums.length - 1);
	}

	public void reverse(int[] n, int s, int e) {
		while (s < e) {
			int c = n[s];
			n[s] = n[e];
			n[e] = c;
			s++;
			e--;
		}

	}
}

4.一些总结：