Description
Numbers can be regarded as the product of their factors.
- For example,
8 = 2 x 2 x 2 = 2 x 4.
Given an integer n, return all possible combinations of its factors. You may return the answer in any order.
Note that the factors should be in the range [2, n - 1].
Example 1:
Input: n = 1
Output: []
Example 2:
Input: n = 12
Output: [[2,6],[3,4],[2,2,3]]
Example 3:
Input: n = 37
Output: []
Constraints:
Solutions
Solution 1
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17 | class Solution:
def getFactors(self, n: int) -> List[List[int]]:
def dfs(n, i):
if t:
ans.append(t + [n])
j = i
while j * j <= n:
if n % j == 0:
t.append(j)
dfs(n // j, j)
t.pop()
j += 1
t = []
ans = []
dfs(n, 2)
return ans
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24 | class Solution {
private List<Integer> t = new ArrayList<>();
private List<List<Integer>> ans = new ArrayList<>();
public List<List<Integer>> getFactors(int n) {
dfs(n, 2);
return ans;
}
private void dfs(int n, int i) {
if (!t.isEmpty()) {
List<Integer> cp = new ArrayList<>(t);
cp.add(n);
ans.add(cp);
}
for (int j = i; j <= n / j; ++j) {
if (n % j == 0) {
t.add(j);
dfs(n / j, j);
t.remove(t.size() - 1);
}
}
}
}
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23 | class Solution {
public:
vector<vector<int>> getFactors(int n) {
vector<int> t;
vector<vector<int>> ans;
function<void(int, int)> dfs = [&](int n, int i) {
if (t.size()) {
vector<int> cp = t;
cp.emplace_back(n);
ans.emplace_back(cp);
}
for (int j = i; j <= n / j; ++j) {
if (n % j == 0) {
t.emplace_back(j);
dfs(n / j, j);
t.pop_back();
}
}
};
dfs(n, 2);
return ans;
}
};
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19 | func getFactors(n int) [][]int {
t := []int{}
ans := [][]int{}
var dfs func(n, i int)
dfs = func(n, i int) {
if len(t) > 0 {
ans = append(ans, append(slices.Clone(t), n))
}
for j := i; j <= n/j; j++ {
if n%j == 0 {
t = append(t, j)
dfs(n/j, j)
t = t[:len(t)-1]
}
}
}
dfs(n, 2)
return ans
}
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