LeetCode 60. Permutation Sequence

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题目

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 for n = 3:

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

Given n and k, return the k^th permutation sequence.

Note:

  • Given n will be between 1 and 9 inclusive.
  • Given k will be between 1 and n! inclusive.

Example 1:

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Input: n = 3, k = 3
Output: "213"

Example 2:

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Input: n = 4, k = 9
Output: "2314"

思路

permutations.

代码

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class Solution(object):
    def getPermutation(self, n, k):
        """
        :type n: int
        :type k: int
        :rtype: str
        """
        x={1:'1',2:'12',3:'123',4:'1234',5:'12345',6:'123456',7:'1234567',8:'12345678',9:'123456789'}
        return ["".join(i) for i in permutations(x[n])][k-1]