Given an array of distinct integers candidates and a target integer target, return a list of all combinations of candidates where the chosen numbers sum to target. You may return the combinations in any order.
The same number may be chosen from candidates an unlimited number of times.
Example 1:
Input:
candidates = [2,3,6,7], target = 7
Output:
[[2,2,3],[7]]
Solution:
public class Solution {
public IList<IList<int>> CombinationSum(int[] candidates, int target) {
List<IList<int>> ans = new List<IList<int>>();
BackTrack(candidates,0, target,new List<int>(), ans);
return ans;
}
public void BackTrack(int[] cand, int start,int target,List<int> list, List<IList<int>> result)
{
if (target < 0)
return;
if (target == 0)
result.Add(new List<int>(list));
for (int i = start; i < cand.Length; i++)
{
list.Add(cand[i]);
BackTrack(cand, i, target - cand[i], list, result);
list.RemoveAt(list.Count-1);
}
}
}