码迷,mamicode.com
首页 > 其他好文 > 详细

LeetCode——Permutation Sequence

时间:2017-07-02 15:16:52      阅读:123      评论:0      收藏:0      [点我收藏+]

标签:tostring   art   sel   tps   not   return   round   problems   div   

The set [1,2,3,…,n] contains a total of n! unique permutations.

By listing and labeling all of the permutations in order,
We get the following sequence (ie, for n = 3):

  1. "123"
  2. "132"
  3. "213"
  4. "231"
  5. "312"
  6. "321"

Given n and k, return the kth permutation sequence.

Note: Given n will be between 1 and 9 inclusive.

原题链接:https://oj.leetcode.com/problems/permutation-sequence/

从n个数的全排列中找出第k个排列。

n开头的排列有(n-1)!个。

k/(n-1)!可确定第一个数字,在余下的(n-1)!中找k%(n-1)!个。

public class PermutationSequence {
	public String getPermutation(int n, int k) {
		List<Integer> list = new ArrayList<Integer>();
		for(int i=1;i<=n;i++)
			list.add(i);
		int mod = 1;
		for (int i = 1; i <= n; i++) {
			mod = mod * i;
		}
		k--;
		StringBuilder builder = new StringBuilder();
		for(int i=0;i<n;i++){
			mod /= (n-i);
			int index = k / mod;
			k %= mod;
			builder.append(list.get(index));
			list.remove(index);
		}
		return builder.toString();
	}
}

LeetCode——Permutation Sequence

标签:tostring   art   sel   tps   not   return   round   problems   div   

原文地址:http://www.cnblogs.com/yxysuanfa/p/7105940.html

(0)
(0)
   
举报
评论 一句话评论(0
登录后才能评论!
© 2014 mamicode.com 版权所有  联系我们:gaon5@hotmail.com
迷上了代码!