LeetCode-Permutation Sequence

最新推荐文章于 2020-01-08 22:54:53 发布

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最新推荐文章于 2020-01-08 22:54:53 发布

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本文链接：https://blog.youkuaiyun.com/HolyDominat/article/details/38541505

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本文介绍了一种算法，用于找出从1到n的所有唯一排列中的第k个排列。通过列举并按顺序标记所有可能的排列，可以得到所需的排列序列。文章提供了具体的实现代码。

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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):

"123"
"132"
"213"
"231"
"312"
"321"

Given n and k, return the kth permutation sequence.

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

Solution:

Code:

<span style="font-size:14px;">class Solution {
public:
    string getPermutation(int n, int k) {
        vector<int> nums(n, 1);
        int t = 1;
        for (int i = 2; i <= n; ++i) {
            nums[i-1] = i;
            t *= i;
        }
        t /= n;
        --k;
        string result;
        while (n > 1) {
            int q = k/t;
            k = k%t;
            --n;
            t = t/n;
            result += '0'+nums[q];
            nums.erase(nums.begin()+q);
        }
        result += '0'+nums[0];
        return result;
    }
};</span>