[leetcode] Combination Sum III

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

public class Solution { List<List<Integer>> result = new ArrayList<List<Integer>>(); int k; public List<List<Integer>> combinationSum3(int k, int n) { this.k = k; rec(0, 1, n, new ArrayList<Integer>()); return result; } private void rec(int count, int start, int target, List<Integer> fromPrev){ if (count == k && target == 0){ result.add(new ArrayList<Integer>(fromPrev)); } if (count == k) return; for (int i = start; i < 10; i++){ fromPrev.add(i); rec(count+1, i+1, target-i, fromPrev); fromPrev.remove(fromPrev.size()-1); } } }