题目描述
blablabla
样例
blablabla
算法1
(暴力枚举) $O(n^2)$
blablabla
时间复杂度
参考文献
C++ 代码
class Solution {
public:
vector<vector<int>> combine(int n, int k) {
vector<int> path;
vector<vector<int>> ans;
function<void(int)> dfs = [&](int start) {
if (path.size() == k) {
ans.push_back(path);
return;
}
for (int i = start; i <= n - (k - path.size()) + 1; i++) {
path.push_back(i);
dfs(i + 1);
path.pop_back();
}
};
dfs(1);
return ans;
}
};
算法2
(暴力枚举) $O(n^2)$
blablabla
时间复杂度
参考文献
Java 代码
import java.util.ArrayList;
import java.util.List;
class Solution {
public List<List<Integer>> combine(int n, int k) {
List<Integer> path = new ArrayList<>();
List<List<Integer>> ans = new ArrayList<>();
dfs(1, n, k, path, ans);
return ans;
}
private void dfs(int start, int n, int k, List<Integer> path, List<List<Integer>> ans) {
if (path.size() == k) {
ans.add(new ArrayList<>(path));
return;
}
for (int i = start; i <= n - (k - path.size()) + 1; i++) {
path.add(i);
dfs(i + 1, n, k, path, ans);
path.remove(path.size() - 1);
}
}
}