Permutation Sequence
Desicription
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
代码语言：javascript复制class Solution {
public:
string getPermutation(int n, int k) {
string res;
vector<int> nums(n), f(n);
for (int i=0; i<n; i ) nums[i]=i 1;
f[0]=1;
for (int i=1; i<n; i ) f[i]=f[i-1]*i;
k--;
for (int i=n-1; i>=0; i--) {
int j=k/f[i];
res =nums[j] '0';
nums.erase(nums.begin() j);
k%=f[i];
}
return res;
}
};
