LeetCode：39. Combination Sum（Medium）

1. 原题链接

https://leetcode.com/problems/combination-sum/description/

2. 题目要求

给定一个整型数组candidates[ ]和目标值target，找出数组中累加之后等于target的所有元素组合

注意：（1）数组中的每一个元素可以重复用；（2）数组中不存在重复元素；（3）数组中都是正整数

3. 解题思路

采用迭代的方法检验所有元素组合

4. 代码实现

 import java.util.ArrayList;
 import java.util.List;

 public class CombinationSum39 {
     public static void main(String[] args) {
         CombinationSum39 cs = new CombinationSum39();
         int[] candidates = {,,,};
         for (List l1:cs.combinationSum(candidates,)){
             System.out.println(l1.toString());
             System.out.println();
         }

     }
     public List<List<Integer>> combinationSum(int[] candidates, int target) {
         List<List<Integer>> result = new ArrayList<List<Integer>>();
         combinationSum(result,new ArrayList<Integer>(),candidates,target,);
         return result;
     }
     public void combinationSum(List<List<Integer>> result, List<Integer> cur, int[] candidates, int target,int start) {
         if (target > ) {
             for (int i = start;i < candidates.length;i++) {
                 cur.add(candidates[i]);
                 combinationSum(result, cur, candidates, target-candidates[i],i);
                 cur.remove(cur.size() - );
             }
         }
         if (target == )
             result.add(new ArrayList<Integer>(cur));
     }
 }