Circular Permutation in Binary Representation LeetCode solution in C++

1
class Solution {
2
 public:
3
  vector<string> get_val(int n) {
4
    if (n == 1) return {"0", "1"};
5
    vector<string> v = get_val(n - 1);
6
    vector<string> ans;
7
    for (int i = 0; i < v.size(); i++) {
8
      ans.push_back("0" + v[i]);
9
    }
10

11
    for (int i = v.size() - 1; i >= 0; i--) {
12
      ans.push_back("1" + v[i]);
13
    }
14
    return ans;
15
  }
16

17
  vector<int> solve(int n) {
18
    vector<string> v = get_val(n);
19
    vector<int> ans;
20
    for (int i = 0; i < v.size(); i++) {
21
      string s = v[i];
22
      int x = 0;
23
      for (int j = 0; j < s.size(); j++) {
24
        x = x * 2 + s[j] - '0';
25
      }
26
      ans.push_back(x);
27
    }
28
    return ans;
29
  }
30

31
  vector<int> circularPermutation(int n, int start) {
32
    vector<int> v = solve(n);
33
    int ind;
34
    for (int i = 0; i < v.size(); i++) {
35
      if (v[i] == start) {
36
        ind = i;
37
        break;
38
      }
39
    }
40

41
    vector<int> ans;
42
    for (int i = ind; i < v.size(); i++) {
43
      ans.push_back(v[i]);
44
    }
45
    for (int i = 0; i < ind; i++) {
46
      ans.push_back(v[i]);
47
    }
48
    return ans;
49
  }
50
};