[Leetcode] Permutation Sequence

Narrative description of the problem:

The set [1,2,3,…,n] contains a total ofn! 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 would be between 1 and 9 inclusive.

Basic idea:

According to K and n! , the k sequence should raise several numbers in which position.

Code:

Consider if k > n!?      string getpermutation (int n, int k) {   //c++        //the first        vector<char> base (n, ' 0 ');         for (int i = 1; i<=n; i++)            base[i-1] = i + ' 0 ';                Vector<int> multi (n);        int temp = 1;        Multi[0] = 1;        for (int i =1; i < n; i++) {            temp *= i;            Multi[i] = temp;        }                k--;        for (int i = 0; i< n-1; i++) {            int temp = k/multi[n-i-1];                        int pos = i+temp;            char C = base[pos];                        for (Int J =pos-1; j>=i; j--)                base[j+1] = base[j];                            Base[i] = C;            k = k%multi[n-i-1];        }                To string        string result = "";        for (int i = 0; i < n; i++)            result + = (base[i]);        return result;    }

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[Leetcode] Permutation Sequence