day24 打卡第77题. 组合
第77题. 组合
class Solution {
List<List<Integer>> result = new ArrayList<>();
List<Integer> path = new LinkedList<>();
public List<List<Integer>> combine(int n, int k) {
combineHelper(n, k , 1);
return result;
}
private void combineHelper(int n, int k, int startIndex){
if (path.size() == k) {
result.add(new ArrayList(path));
return;
}
for (int i = startIndex ; i<=n - (k - path.size()) + 1 ; i++) {
path.add(i);
combineHelper(n, k, i+1);
path.remove(path.size()-1);
}
}
}